Description

All Test For Geosci

Andriana geosci1. The US government, and most other governments of the world, provide support
for scientists but not for astrologers, palm readers, or telephone “psychics”. Why do governments support
scientists?
A. Scientists help humans do useful things, which makes the humans healthier, wealthier, etc., and
governments often like to support health and wealth.
B. Scientists use a careful method, and governments are always committed to supporting the use of
careful methods.
C. Scientists all drink Diet Pepsi because they think it makes them look sexy, and governments are all
controlled by the powerful Pepsi Corporation and so the governments support the DietPepsidrinking
scientists.
D. Scientists are amazingly sexy, and government functionaries simply cannot control themselves in the
presence of such overwhelming sexiness and throw money at the scientists (sometimes tucking tens and
twenties into the pockets of the scientists’ lab coats).
E. Scientists learn the Truth, and governments are always deeply committed to learning the truth.
The government is often interested in seeing people live longer, or improving the economy, or having
better and moreaccurate
explosive devices for the military, or in many other things that improve our lives,
and science plus engineering and scientific medicine are better than any other human activity at delivering
these. A cynic might say that politicians are often not all that interested in finding the Truth. And a realist
would note that science is being improved all the time, and because you cannot improve on the Truth,
science has not (yet?) learned the Truth. There are many methods in the world, some of them are careful,
and many of them are not funded by the government. Some of our spouses or significant others may think
that some scientists are sexy, but many other sexy persons are not funded by the government. One of the
professors has been known to drink a competitor of Pepsi on occasion, and some scientists refrain from
soft drinks entirely.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
2., A scientist gains knowledge about how the world works, and uses that information to successfully
predict what will happen in an experiment. This proves that the scientist’s knowledge is:
, A., Close; no one really knows what is going on, but people sort of know.
B., Cheating.
C., True; you can’t get it right unless you know what is going on.
D., One or more of True, lucky, or close to being true (or cheating), but we can’t tell which.
E., Lucky; no one knows what is going on, so only lucky people get things right.
If you guessed “heads” before a coin flip, and it came up heads, that would NOT prove that you can
predict all coin flips; you will get half of such guesses correct by chance. You might be cheating, you might
be lucky, or you might have figured something out.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
3., The great scientist Alfred Wegener proposed that continents have moved, while other scientists such
as T.C. Chamberlin argued against Wegener. Wegener’s ideas eventually won, and are now widely
accepted, because:
, A., Wegener’s ideas appealed to dead white European males, whereas Chamberlin’s didn’t.
B., Wegener’s ideas appalled dead white European males, and we all know that in this politically correct
era, dead white European males cannot get a fair shake.
C., Wegener won the Nobel prize.
D., Wegener’s ideas did a better job of predicting the results of new observations and experiments.
E., Wegener’s ideas were more beautiful, and so were favored by the intellectual elite.
Unlike painting or literature, scientific inquiry has a welldefined
procedure for figuring out if Wegener’s
ideas are better or if Chamberlin had it right all along. In looking at a painting, we can ask different people
what they think, or we can make up our own mind on whether we like it or not, and that is perfectly valid.
In science, we have to ask: does the idea fit with the way the world works? Can I predict the results of the
next observation better using Wegener’s ideas or Chamberlin’s? As it turns out, Chamberlin’s ideas didn’t
predict things very well, and Wegener’s did.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
4., Science professors teach certain theories and not others (Newton’s physics, and not Aristotle’s, or
Darwin’s evolution and not Lamarck’s). If you were to ask the professors why, a majority would tell you
(more or less; not using exactly these words but with this meaning):
, A., “Lamarck and Aristotle are so rightwing,
and you know all of us professors are part of a vast leftwing
conspiracy.”
B., “Nature has repeatedly been asked (through experiment) which is better, and we are teaching the
ones that made successful predictions, and not teaching the ones that failed.”
C., “Hey, I’m the professor, shut up.”
D., “Lamarck and Aristotle are so leftwing,
and you know all of us professors are part of a vast rightwing
conspiracy cleverly dressed up to look like a vast leftwing
conspiracy.”
E., “Well, we have to teach something in exchange for all those wads of cash you students pay, and this is
more fun.”
You can be quite confident that the bigpicture
items in science class have been tested against reality and
found to work. There still might be someone in academe who would reply with B (your professors
remember a couple of their professors who could have said such a thing) (the technical term for anyone
who would reply with the quote in B is “jerk”), but that is pretty rare today.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
5., Your boss has assigned you to get the lowdown
on the latest wonderdrug,
and to be darn sure to get
it right. You would be wise to consult:
, A., The web site of the manufacturer of the wonder drug; they know more about it than anyone else
does.
B., The New York Times article quoting the discoverer of the drug on how wonderful it is.
C., The Wikipedia; everything they publish is uptodate.
D., The web site in the email you received with the subject line “Grow your ***** naturally with new wonder
drug”.
E., The article in the Journal of the American Medical Society, a peerreviewed
scientific journal, reporting
on the discovery and testing of the drug.
No source of information is perfect, but the refereed articles in learned journals put immense effort into
“getting it right”. The web has some reliable information, but probably most of the information on the web
is not especially reliable. The web is very inexpensive, and lots of people put junk on it. The Wikipedia
gets a lot of things right, but it is a distilled synopsis of the real stuff. Most newspapers are around for the
long haul, and try to make the news fairly accurate, although some newspapers do have agendas, and
the editorial pages are not especially accurate. But, if the report is on the views of a public figure, the
newspaper may accurately report what the public figure said, but what the public figure said may be less
than completely accurate. And while you are welcome to believe that an unsolicited email promising to
grow your ***** will do so… don’t count on it.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
6., The peer review process, in which scientists submit writeups
of their ideas and experiments to a set of
colleagues who judge how good the ideas are before the ideas can be published, is:
, A., The way all publications do business, including the popular press such as the New York Times,
Centre Daily Times, National Enquirer, etc.
B., Always infallible.
C., A way to keep unpopular or dangerous ideas out of public circulation.
D., A way for the Scientific Establishment to maintain control over ideas and theories.
E., A useful and important, even if imperfect, mechanism of qualitycontrol
for the scientific literature.
The peer review process applies to scientific publications and works like this: I get an idea and do some
experiments to test it and write down the results of the tests. I send the paper to a scientific journal
(Nature, Journal of Geophysical Research, etc.) and the editor of the journal sends it to a number of other
scientists who can best judge whether my methods are good, whether my results are new and interesting,
and whether my paper ought to be published. They don’t base their judgements on whether they like me
or not or whether I’m a nice guy/gal or not (or at least they ought not base their judgments on that, though
it does happen: we’re human!). They don’t base their judgements on whether my ideas are popular or
unpopular. They are only supposed to ask: is this really new (i.e., did somebody else think of this and
publish it already somewhere else?) and are the methods used accurate and repeatable?
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
7., If you could drill a hole straight to the center of the Earth, and keep track of what the hole is going
through, you would find:
, A., If your hole started at the North Pole, you would go through different layers of different materials, but
if your hole started at the equator, you would go through one sort of material all the way to the center.
B., You would go through one sort of material all the way to the center, because the planet is all mixed up.
C., You would strike Diet Pepsi when you got to the center.
D., If your hole started at the equator, you would go through different layers of different materials, but if
your hole started at the North Pole, you would go through one sort of material all the way to the center.
E., You would go through one sort of material, and then a different, denser material, and then a stilldifferent,
stilldenser
material, because the planet is made of concentric layers, sort of like an onion.
The planet is onionlike,
with an inner core, then an outer core, a mantle (which has several sublayers),
and a crust. The core is waaaaay too hot and highpressure
for Diet Pepsi.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
8., The scientific study of the origin of the planet has taken a lot of effort, and still generates much discord
outside the scientific community although almost no discord within the scientific community. The
scientifically accepted history is:
, A., The Earth formed from older materials that fell together under gravity about 6000 years ago.
B., The Earth formed three minutes after the Big Bang, as the cosmic microwave background radiation
cooled off, about 14 billion years ago, as chronicled in Steven Weinberg’s famous book “The First Three
Minutes”.
C., The Earth was formed from the deepspace
wind, generated by the gaspassing
activities of giant
space marmots, about 4.6 billion years ago.
D., The Earth formed from older materials that fell together under gravity about 4.6 billion years ago.
E., The Earth formed in the Big Bang about 6000 years ago.
The Big Bang is estimated as having occurred about 14 billion years ago. Stars that eventually formed in
the wake of the Big Bang led to production of elements such as iron and silicon that are common in the
Earth—we are formed from secondgeneration
stardust, which “got it together” to make the planet about
4.6 billion years ago.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
9., National Parks are:
, A., Regions containing key geological resources that have been set aside for the enjoyment of future
generations.
B., Regions containing key bumpercars
games that have been set aside for the enjoyment of the current
presidential administration.
C., Regions containing key biological resources that have been set aside for the enjoyment of the present
generation.
D., Regions containing key cultural resources that have been set aside for the enjoyment of the present
generation.
E., Regions containing key biological, geological or cultural resources that have been set aside for the
enjoyment of the present generation and future generations.
Old Faithful, the giant sequoias, and Mesa Verde’s cliff dwellings are waiting for you, and your
grandchildren.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
10., In chemistry, the type of an atom (what element it is) is determined by:
, A., The number of protons it has in a cloud around the nucleus.
B., The number of neutrons it has in a cloud around the nucleus.
C., The number of electrons it exchanges with its neighbors.
D., The number of neutrons it contains in its nucleus.
E., The number of protons it contains in its nucleus.
Physicists change the name when the number of charged, massive protons in the nucleus changes.
Adding one proton makes a HUGE difference to how an atom behaves, and so deserves a new name.
The neutrons hang around in the nucleus to keep the protons from kicking each other out. Exchanging
electrons is important, but doesn’t change the element type.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
11., Chemists recognize many different elements, such as gold, or oxygen, or carbon. Suppose you got
some carbon, and started splitting it into smaller pieces. The smallest piece that would still be called
“carbon” would be:
, A., An electron
B., A neutron
C., A proton
D., A quark
E., An atom
We can break matter down into atoms (Greek for “not cuttable” because the Greeks didn’t have atom
smashers or other exotic tools that would allow cutting atoms into smaller pieces). All of the wrong
answers here are smaller pieces of atoms, but they wouldn’t be gold any more; you can make any of the
elements out of these pieces.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
12., Chemical reactions involve:
, A., The sharing or trading of neutrons.
B., The sharing or trading of partons.
C., The sharing or trading of protons.
D., The sharing or trading of electrons.
E., The sharing or trading of quarks.
The clouds of electrons around the nuclei of atoms serve as the Velcro of the universe. Atoms gain or lose
electrons and then stick together by static electricity, or else share electrons and stick together inside the
shared cloud. The nuclei with their protons and neutrons (which are themselves composed of quarks,
which also were called partons at one time) are the things held together by the electronic Velcro of
chemistry.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
///, 11
Points Missed, 0
Percentage, 100%
1., Scientists receive government funding primarily because:
, A., They use a careful method.
B., They are all sexy.
C., They help humans do useful things.
D., They learn the Truth.
E., They all drink Diet Pepsi because they think it makes them look sexy.
The government is often interested in seeing people live longer, or improving the economy, or having better and
more-accurate explosive devices for the military, or in many other things that improve our lives, and science plus
engineering and scientific medicine are better than any other human activity at delivering these. A cynic might say
that politicians are often not all that interested in finding the Truth. And a realist would note that science is being
improved all the time, and because you cannot improve on the Truth, science has not (yet?) learned the Truth. There
are many methods in the world, some of them are careful, and many of them are not funded by the government.
Some of our spouses or significant others may think that some scientists are sexy, but many other sexy persons are
not funded by the government. One of the professors has been known to drink a competitor of Pepsi on occasion,
and some scientists refrain from soft drinks entirely.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
2., You hang around with the professor, who is a scientist when he’s not teaching. You observe that the professor
learns a lot about how certain parts of the world behave, and the professor then uses that information to successfully
predict the outcome of an experiment. What does this demonstrate?
, A., The professor’s knowledge is close to being True; no professor really knows what is going on, but some
professors are sort of close to knowing what is going on.
B., The professor was lucky; no professor could ever know what is going on, so a professor who successfully
predicted something must be really lucky.
C., The professor’s knowledge is True; the professor couldn’t have made the successful prediction without knowing
exactly what is going on.
D., Unless the professor was cheating, the professor either has true knowledge, or was lucky, or has knowledge that
is at least close to being correct, but you cannot tell which.
E., The professor cheated; no professor could get anything right without cheating.
If you guessed “heads” before a coin flip, and it came up heads, that would NOT prove that you can predict all coin
flips; you will get half of such guesses correct by chance. You might be cheating, you might be lucky, or you might
have figured something out.
Correct Answer:,
Your Response:, D
3., The great scientist Alfred Wegener proposed that continents have moved, while other scientists such as T.C.
Chamberlin argued against Wegener. Wegener’s ideas eventually won, and are now widely accepted, because:
, A., Wegener’s ideas appealed to dead white European males, whereas Chamberlin’s didn’t.
B., Wegener’s ideas did a better job of predicting the results of new observations and experiments.
C., Wegener won the Nobel prize.
D., Wegener’s ideas appalled dead white European males, and we all know that in this politically correct era, dead
white European males cannot get a fair shake.
E., Wegener’s ideas were more beautiful, and so were favored by the intellectual elite.
Unlike painting or literature, scientific inquiry has a well-defined procedure for figuring out if Wegener’s ideas are
better or if Chamberlin had it right all along. In looking at a painting, we can ask different people what they think, or
we can make up our own mind on whether we like it or not, and that is perfectly valid. In science, we have to ask:
does the idea fit with the way the world works? Can I predict the results of the next observation better using
Wegener’s ideas or Chamberlin’s? As it turns out, Chamberlin’s ideas didn’t predict things very well, and Wegener’s
did.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
4., Science professors teach certain theories and not others (Newton’s physics, and not Aristotle’s, or Darwin’s
evolution and not Lamarck’s). If you were to ask the professors why, a majority would tell you (more or less; not
using exactly these words but with this meaning):
, A., “Lamarck and Aristotle are so right-wing, and you know all of us professors are part of a vast left-wing
conspiracy.”
B., “Well, we have to teach something in exchange for all those wads of cash you students pay, and this is more
fun.”
C., “Lamarck and Aristotle are so left-wing, and you know all of us professors are part of a vast right-wing
conspiracy cleverly dressed up to look like a vast left-wing conspiracy.”
D., “Hey, I’m the professor, shut up.”
E., “Nature has repeatedly been asked (through experiment) which is better, and we are teaching the ones that made
successful predictions, and not teaching the ones that failed.”
You can be quite confident that the big-picture items in science class have been tested against reality and found to
work. There still might be someone in academe who would reply with B (your professors remember a couple of
their professors who could have said such a thing) (the technical term for anyone who would reply with the quote in
B is “jerk”), but that is pretty rare today.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
5., Your boss has assigned you to get the low-down on the latest wonder-drug, and to be darn sure to get it right. You
would be wise to consult:
, A., The article in the Journal of the American Medical Society, a peer-reviewed scientific journal, reporting on the
discovery and testing of the drug.
B., The Wikipedia; everything they publish is up-to-date.
C., The New York Times article quoting the discoverer of the drug on how wonderful it is.
D., The web site of the manufacturer of the wonder drug; they know more about it than anyone else does.
E., The web site in the email you received with the subject line “Grow your ***** naturally with new wonder drug”.
No source of information is perfect, but the refereed articles in learned journals put immense effort into “getting it
right”. The web has some reliable information, but probably most of the information on the web is not especially
reliable. The web is very inexpensive, and lots of people put junk on it. The Wikipedia gets a lot of things right, but
it is a distilled synopsis of the real stuff. Most newspapers are around for the long haul, and try to make the news
fairly accurate, although some newspapers do have agendas, and the editorial pages are not especially accurate. But,
if the report is on the views of a public figure, the newspaper may accurately report what the public figure said, but
what the public figure said may be less than completely accurate. And while you are welcome to believe that an
unsolicited email promising to grow your ***** will do so… don’t count on it.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
6., The peer review process, in which scientists submit write-ups of their ideas and experiments to a set of
colleagues who judge how good the ideas are before the ideas can be published, is:
, A., The way all publications do business, including the popular press such as the New York Times, Centre Daily
Times, National Enquirer, etc.
B., A way to keep unpopular or dangerous ideas out of public circulation.
C., Always infallible.
D., A way for the Scientific Establishment to maintain control over ideas and theories.
E., A useful and important, even if imperfect, mechanism of quality-control for the scientific literature.
The peer review process applies to scientific publications and works like this: I get an idea and do some experiments
to test it and write down the results of the tests. I send the paper to a scientific journal (Nature, Journal of
Geophysical Research, etc.) and the editor of the journal sends it to a number of other scientists who can best judge
whether my methods are good, whether my results are new and interesting, and whether my paper ought to be
published. They don’t base their judgements on whether they like me or not or whether I’m a nice guy/gal or not (or
at least they ought not base their judgments on that, though it does happen: we’re human!). They don’t base their
judgements on whether my ideas are popular or unpopular. They are only supposed to ask: is this really new (i.e.,
did somebody else think of this and publish it already somewhere else?) and are the methods used accurate and
repeatable?
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
7., If you could drill a hole straight to the center of the Earth, and keep track of what the hole is going through, you
would find:
, A., You would go through one sort of material, and then a different, denser material, and then a still-different, stilldenser
material, because the planet is made of concentric layers, sort of like an onion.
B., If your hole started at the North Pole, you would go through different layers of different materials, but if your
hole started at the equator, you would go through one sort of material all the way to the center.
C., If your hole started at the equator, you would go through different layers of different materials, but if your hole
started at the North Pole, you would go through one sort of material all the way to the center.
D., You would strike Diet Pepsi when you got to the center.
E., You would go through one sort of material all the way to the center, because the planet is all mixed up.
The planet is onion-like, with an inner core, then an outer core, a mantle (which has several sub-layers), and a crust.
The core is waaaaay too hot and high-pressure for Diet Pepsi.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
8., The scientific study of the origin of the planet has taken a lot of effort, and still generates much discord outside
the scientific community although almost no discord within the scientific community. The scientifically accepted
history is:
, A., The Earth formed three minutes after the Big Bang, as the cosmic microwave background radiation cooled off,
about 14 billion years ago, as chronicled in Steven Weinberg’s famous book “The First Three Minutes”.
B., The Earth formed from older materials that fell together under gravity about 6000 years ago.
C., The Earth formed in the Big Bang about 6000 years ago.
D., The Earth formed from older materials that fell together under gravity about 4.6 billion years ago.
E., The Earth was formed from the deep-space wind, generated by the gas-passing activities of giant space marmots,
about 4.6 billion years ago.
The Big Bang is estimated as having occurred about 14 billion years ago. Stars that eventually formed in the wake of
the Big Bang led to production of elements such as iron and silicon that are common in the Earth—we are formed
from second-generation stardust, which “got it together” to make the planet about 4.6 billion years ago.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
9., National Parks are:
, A., Regions containing key geological resources that have been set aside for the enjoyment of future generations.
B., Regions containing key biological, geological or cultural resources that have been set aside for the enjoyment of
the present generation and future generations.
C., Regions containing key bumper-cars games that have been set aside for the enjoyment of the current presidential
administration.
D., Regions containing key cultural resources that have been set aside for the enjoyment of the present generation.
E., Regions containing key biological resources that have been set aside for the enjoyment of the present generation.
Old Faithful, the giant sequoias, and Mesa Verde’s cliff dwellings are waiting for you, and your grandchildren.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
10., You find an atom, and you want to learn what element it is (its fundamental type). If you are efficient, you first
should:
, A., Count the number of protons contained in the cloud around the nucleus of the atom.
B., Count the number of protons contained in the nucleus of the atom.
C., Count the number of neutrons contained in the cloud around the nucleus of the atom.
D., Count the number of electrons that the atom has exchanged with its neighbors.
E., Count the number of neutrons contained in the nucleus of the atom.
Physicists change the name when the number of charged, massive protons in the nucleus changes. Adding one
proton makes a HUGE difference to how an atom behaves, and so deserves a new name. The neutrons hang around
in the nucleus to keep the protons from kicking each other out. Exchanging electrons is important, but doesn’t
change the element type.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
11., Chemists recognize many different elements, such as gold, or oxygen, or carbon, or iron. Suppose you got some
iron, and started splitting it into smaller pieces. The smallest piece that would still be called “iron” would be:
, A., A proton
B., A quark
C., An atom
D., A neutron
E., An electron
We can break matter down into atoms (Greek for “not cuttable” because the Greeks didn’t have atom smashers or
other exotic tools that would allow cutting atoms into smaller pieces). All of the wrong answers here are smaller
pieces of atoms, but they wouldn’t be gold any more; you can make any of the elements out of these pieces.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
12., Nuclei of atoms are made up of:
, A., Protons.
B., Protons, usually with neutrons added.
C., Protons, usually with electrons added.
D., Neutrons.
E., Neutrons, usually with electrons added.
The simplest nucleus is the single proton in “ordinary” hydrogen. All other nuclei include protons and neutrons.
Electrons make the cloud around the nucleus.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
///, 14
Points Missed, 1
Percentage, 93%
,
1., Dave Janesko is explaining the great Sevier Fault to Dr. Alley and the CAUSE class.
Dave has just informed everyone that the black rocks, which formed by cooling of a very hot lava flow, are
much younger than the red rocks, which formed from sediments deposited in a lake. He has examined the
red rocks and found that they have not been “cooked” by heat from the black rocks, so the red and black
rocks must have been placed together after the black rocks cooled. And, he has examined the contact
between red and black rocks and found that it is a fault that has been scratched by the motion of the rocks
along the fault. It is likely that:
, A., The scratches are nearly vertical, because the black rocks were dropped down along a pullapart
fault to lie next to the red rock.
B., The scratches are all horizontal, because the red rocks moved over the black rocks in a landslide.
C., The scratches are nearly vertical, because the black rocks were pushed up from below along a pushtogether
fault to lie next to the red rocks.
D., The scratches make little curlicues, because motion on the fault screwed the two sides together.
E., The scratches are nearly horizontal, because the black rocks were slid in from the side along a slidepast
fault.
The spreading that opened Death Valley affected a lot of the west, all the way over to Bryce Canyon in
Utah. The Sevier Fault, just west of Bryce, formed as pullapart
action broke the rocks, allowing younger
rocks including the black lava flow to drop down next to older rocks including the red lake sediments. The
scratches are not too far from vertical, made as the rocks dropped down.
, Points Earned:, 1/1
Your Response:, A
2., The processes that made Death Valley continue to operate today. For this question, ignore the sand
and gravel moved by water and wind, and think about the big motions of the rocks beneath. Choose the
best answer: what are they doing to the valley?
, A., Death Valley is getting narrower
B., Death Valley is getting shallower.
C., Death Valley is getting narrower and shallower.
D., Death Valley is getting wider and deeper.
E., Death Valley is not changing.
The pullapart
action that is spreading Death Valley and surroundings also involves uplift of mountains or
downdrop of valleys, and Death Valley has dropped as its flanking mountains have moved apart.
, Points Earned:, 1/1
Your Response:, D
3., 20mule
teams hauled borax salts out of Death Valley, and the valley still has lots of salt, sand, and
river gravel in the bottom. The most likely explanation is:
, A., Wind and rivers cut the valley deep, and after the river dried up, the river gravel, salt and sand were
left behind.
B., The valley was dropped relative to the mountains by faulting, and rivers have been (and still are)
carrying gravel, sand and salts down from the mountains into the valley.
C., The valley was dropped relative to the mountains by faulting; the salts, sand and gravel had been
deposited on mountain tops by rivers and wind before the faulting started, and then were dropped down
by the faulting.
D., The valley was paved with salt, sand and gravel by a movie company for a really spectacular stunt in
the Dukes of Hazzard movie, involving longdistance
car chases and Daisy leaping the boys’ car across
the entire park.
E., The valley was raised by faulting, bringing up the salts, sand and gravel from subterranean caves.
, Points Earned:, 0/1
Your Response:, C
4., Geophysical evidence indicates that convection is occurring in the Earth’s mantle. What is the most
likely physical explanation for why convection can occur in the mantle?
, A., The Earth’s outer core is completely melted, and this stirs the mantle to cause convection.
B., The magnetic field lines from the rotation of the Earth’s solid inner core induce torques in the mantle,
causing convection.
C., Rocks deep in the Earth expand and so become lower in density and tend to rise as they are heated,
and the deep rocks are warm enough to flow slowly even though they are mostly solid.
D., The Earth’s mantle is completely melted, and melting allows convection when heat from below causes
expansion and drop in density of the deep liquid.
E., The Earth is cooled deep inside, causing contraction that raises density, moredense
things tend to
sink, and the mantle rocks are cold enough to flow slowly even though they are not melted.
Convection seems so easy, but describing it in words is not. For “ordinary” convection, one needs
something capable of flowing (gas, liquid, or soft solid), heat below and cold above with expansion
reducing density on heating and contraction increasing density on cooling, and then a bit of time and a
perturbation of some sort to get the motion started. If you had something that expanded on cooling and
contracted on heating, and you had cooling below and warming above, you could also make convection
work. The mantle is mostly solid, the outer core can’t directly stir the mantle or cause convection, and
Graham Spanier was solid and not melted the last time we checked.
, Points Earned:, 1/1
Your Response:, C
5., Heat is moved around by convection, conduction and radiation (and by lemmings carrying space
heaters, if lemmings ever carry space heaters). Which statement is more nearly correct?
, A., Convection moves heat efficiently through the soft, hot rocks of the Earth’s mantle, but is not efficient
at moving heat through the space between the Sun and the Earth.
B., No matter where you are, lemmings carrying space heaters are always moving more heat than
convection is moving.
C., No matter where you are, radiation always moves heat more efficiently than does convection.
D., No matter where you are, conduction always moves heat more efficiently than does convection.
E., Convection moves heat efficiently through the space between the Sun and the Earth, but not through
the soft, hot rocks of the mantle.
Heat from deep in the Earth is moved up through the soft bulk of the planet primarily by convection, but
convection of rocks certainly does not continue beyond the planet, where radiation becomes dominant. In
the shallowest, uppermost layers of the Earth, most of the heat transfer is by conduction. And the poor
lemmings deserve a rest and a snack.
, Points Earned:, 1/1
Your Response:, A
6., People visit Death Valley for all sorts of reasons. Some people even go there to study volcanoes. What
is accurate about those Death Valley volcanoes?
, A., The volcanoes near the edges of Death Valley produce rocks that are similar in composition to the
rocks made by volcanoes at undersea spreading ridges, because Death Valley is in many ways
geologically linked to undersea spreading ridges.
B., The volcanoes of Death Valley produce rocks that are similar in composition to the rocks made by
volcanoes at undersea spreading ridges, because all volcanoes make lava of the same composition.
C., Death Valley has no volcanoes, and has never had volcanoes.
D., The volcanoes of Death Valley produce rocks that are of a completely different composition than the
rocks produced by volcanoes at undersea spreading ridges, because Death Valley is geologically
completely unrelated to undersea spreading ridges.
E., Death Valley has volcanoes that are erupting as this was typed, and have been erupting continuously
for decades, so the next time you’re driving near Vegas, you can go see the lava flowing out.
Death Valley has spreadingridgetype
volcanoes, and if you go south from the Valley, you find the
spreading ridge in the Gulf of California; Death Valley and the Gulf of California are geologically related.
There have been recent eruptions in Death Valley (within the last centuries), but as of this writing, no
volcanoes are currently erupting in Death Valley, nor have any erupted for over a century.
, Points Earned:, 1/1
Your Response:, A
7., Dust and shells and fish poop and all sorts of things fall to the sea bed to make sediment. Across
broad central regions of the ocean, the sediment accumulates at a uniform rate—piling up about as
rapidly here as it does over there. And, in most places, the currents don’t move the sediment around
much, so that it stays where it falls. Thus, the thickness of the sediment is related to the age of the rocks
beneath the sediment. If you go around an ocean and measure the thickness of the sediment in lots of
places, you are likely to find:
, A., The sediment is thin near spreading ridges, and thicker away from the ridges.
B., The sediment thickness varies a lot from place to place, but the pattern is totally random.
C., The sediment is thick near spreading ridges, and thinner away from the ridges.
D., The sediment is the same thickness everywhere.
E., The sediment thickness forms waves, thicker thinner thicker thinner thicker thinner, as you cross the
ocean, but with no influence from spreading ridges.
Sea floor is made at the spreading ridges, and moves away on both sides. Sediment piles up over time,
and while there are variations in sedimentation rate, the huge difference in age of the seafloor
rocks (140
million years near the edges of some ocean basins, to essentially zero at the ridges) is the main
controlling factor on sediment thickness. Fish actually poop wherever they travel, and tend to go all over
the oceans.
, Points Earned:, 1/1
Your Response:, A
8., Most earthquakes in the upper part of the Earth’s crust are caused by elastic rebound, according to
geologists. What do those geologists mean when they say this?
, A., Rocks compressed by volcanic eruptions “bounce back”, shaking their surroundings.
B., Rocks stretched by implosion of subducted slabs then “bounce back”, shaking their surroundings.
C., All rocks on a continent move in the same direction at the same speed, even if there is a fault splitting
the continent.
D., Rocks moving in opposite directions on opposite sides of a fault get stuck for a while and bend, then
“snap back” when something breaks along the fault.
E., Highpressure
water in faults allows the rocks on opposite sides of a fault to move smoothly in
opposite directions all the time, carrying halves of houses built on the faults in opposite directions and so
slowly tearing the houses in half.
Try sliding a boulder over the ground, and you’ll find the boulder gets stuck for a while. Lean harder, the
boulder jerks forward suddenly, and you just had a tiny earthquake. Implosion earthquakes probably exist,
but the rocks don’t bounce back to their original size, and such quakes only can happen deep. We have
no information on Graham Spanier’s choice in socks, but his choice is unlikely to shake much beyond the
immediate vicinity of University Park.
, Points Earned:, 1/1
Your Response:, D
9., On the Richter scale of earthquake intensity:
, A., The ground is shaken 10 times less by a magnitude8
quake than by a magnitude7
quake.
B., The ground is shaken 10 times less by a magnitude7
quake than by a magnitude8
quake.
C., The ground is shaken 8 times more by a magnitude8
quake than by a magnitude1
quake.
D., A magnitude7
quake is impossible; nothing that big can occur.
E., The ground is shaken twice as much by a magnitude8
quake as by a magnitude4
quake.
One problem in describing earthquakes is that the ground shaking in the smallest one you can feel is
1,000,000,000 times smaller than the ground shaking in the largest quakes. We usually dislike having a
scale that requires us to talk about an event of, say, size 100,000,000; instead, if a magnitude1
quake
moves the ground 10 units (say, 10 nanometers at some specified distance from the quake), than we say
that a magnitude2
quake moves the ground 100 units, and a magnitude3
quake moves the ground 1000
units, and so on. You’ll notice that the magnitude is just the number of zeros after the 1; this is a
logarithmic scale.
, Points Earned:, 1/1
Your Response:, B
10., Most of the material moved by volcanoes is from the few, big ones rather then from the many, little
ones. Most of the material moved downhill in landslides is in the many, little ones rather than the few, big
ones. In comparing the importance of the few, big earthquakes to the many, little earthquakes, are
earthquakes more like volcanoes (the few big ones matter most) or like landslides (the many little ones
matter most)?
, A., Earthquakes don’t do any damage, just like volcanoes and landslides.
B., All earthquakes have been retribution for the Simpsons.
C., The many, little earthquakes matter most (like landslides).
D., The few, big earthquakes are just as important as the many, little earthquakes (halfway between
volcanoes and landslides).
E., The few, big earthquakes matter most (like volcanoes).
An increase of 1 in earthquake magnitude increases ground shaking about 10fold,
increases energy
release about 30fold,
and decreases frequency about 10fold;
the 30fold
increase in energy more than
offsets the 10fold
decrease in frequency of occurrence. We wish earthquakes did no damage, but the
millions of people who have been killed in earthquakes over the centuries would, if they could, testify to
the damage done by earthquakes. And historical records of earthquakes clearly preceded the Simpsons.
, Points Earned:, 1/1
Your Response:, E
11., The New Madrid Fault Zone in Missouri has had some surprisingly big earthquakes. A magnetohydroastronomer
at a small university near the fault zone reports that the gravitational effects of the
coming alignment of several planets, together with the weakening of the magnetic field, will cause a giant
earthquake on the fault zone on Wednesday morning between 1 and 4 am. Based on materials presented
in class, you would be wise to:
, A., Invest in the Pepsi Corporation; Pepsi stocks always go up after earthquakes, and an earthquake is
highly likely at the time and place predicted.
B., Get back to whatever you were doing and ignore the forecast; although there might be a very small
effect of planetary gravity or magnetic fields on earthquakes, no one has ever demonstrated the ability to
make such detailed forecasts accurately, and many such forecasts have proven to be wrong.
C., Go to St. Louis with your camera, to photograph the Gateway Arch when it falls during the quake,
because the pictures will be worth a lot of money.
D., Go to California to get your valuable pictures; forecasts of when earthquakes will occur are more
accurate than forecasts of where an earthquake will occur, California is more likely to have a quake, so
you should be there Wednesday to see the damage from the giant quake.
E., Listen up; although the forecast is not certain, such forecasts are usually fairly accurate and should be
heeded.
, Points Earned:, 1/1
Your Response:, B
,
12., The picture above shows a fault in a place where mountains come down near the coast.
What likely happened to form the ramp (also called a scarp) behind the person?
, A., Pullapart
forces shoved one side up over the other, making the break.
B., Slidepast
forces shoved one side up over the other, making the break.
C., Slidepast
forces pulled the rocks apart, making the break, and allowing one side to drop relative to
the other.
D., Pullapart
forces pulled the rocks apart, making the break, and allowing one side to drop relative to the
other.
E., Pushtogether
forces shoved one side up over the other, making the break.
The downside
dropped along the ramp compared to the upside.
(This is actually an interesting one; it
formed in Alaska during the 1964 earthquake. That was a pushtogether
quake, but it was so huge and
moved so much rock in different directions that some of the rock ended up having pullapart
motions,
such as this one.)
, Points Earned:, 1/1
Your Response:, D
13., The Earth includes:
, A., A solid inner core, a liquid outer core, and a mantle with a liquid asthenosphere.
B., A liquid inner core, a solid outer core, and a mantle with a little liquid in a mostly solid asthenosphere.
C., A liquid inner core, a solid outer core, and a mantle with a liquid asthenosphere.
D., A solid inner core, a liquid outer core, and a mantle with a little liquid in a mostly solid asthenosphere.
E., A Pepsi inner core, a Coke outer core, and a mantle of Gatorade drinkers.
High pressure stabilizes solid in the inner core, but the slightly lower pressure on the outer core allows the
iron there to be melted. The ironsilicate
mantle is mostly solid, but a bit of melt occurs in the
asthenosphere. And the great heat of the core would break down both natural and artificial sweeteners,
so cola cannot be found there.
, Points Earned:, 1/1
Your Response:, D
14., What is accurate about seismic waves moving through the Earth?
, A., Swaves
(also called pushwaves
or sound waves) move through all liquids except Diet Pepsi, and pwaves
(also called shearwaves)
move through no liquids except Diet Pepsi.
B., Neither swaves
(also called shearwaves)
nor pwaves
(also called pushwaves
or sound waves)
move through solids.
C., Neither swaves
(also called shearwaves)
nor pwaves
(also called pushwaves
or sound waves)
move through liquids.
D., Swaves
(also called shearwaves)
and pwaves
(also called pushwaves
or sound waves) both move
through liquids.
E., Pwaves
(also called pushwaves
or sound waves) move through liquids and solids, whereas swaves
(also called shear waves) move through solids but not liquids.
Pwaves
go through liquids and solids, because you can squeeze and release a liquid or a solid—push
hear and it squeezes a bit, which squeezes what is next to you… and on in a wave. Swaves
are a bit like
waves on a rope—grab an end and move it sideways, which moves the neighboring part sideways… This
works with solids, but not liquids, which cannot “grab” and move the neighboring part.
, Points Earned:, 1/1
Your Response:, E
,
15., The above diagram is from one of the Geomations in the unit. It shows three possible fault styles. A
and B are crosssections,
with a collapsed building on top to show you which way is up—the yellow band
is a distinctive layer of rock that was broken by the earthquake that also knocked down the building. C is
viewed from a helicopter, looking down on a road with a dashed yellow line down the middle; the road was
broken by an earthquake along the green fault, and the earthquake knocked down a building to make the
funkylooking
brown pile in the upper right. What is accurate about the different earthquake styles?
, A., C is pushtogether,
B is slidepast,
and A is pullapart.
B., C is pullapart,
B is pushtogether,
and A is slidepast.
C., C is slidepast,
B is pullapart,
and A is pushtogether.
D., C is slidepast,
B is pushtogether,
and A is pullapart.
E., C is pushtogether,
B is pullapart,
and A is slidepast.
Imagine putting the image on paper, cutting out the blocks (one block on each side of the fault), and then
sliding them back together to make the original, unbroken features. A and B stand up from the table, C
lies down on the table. Now, slide them to make the picture as seen here. In A, you’ll be moving the righthand
block up and toward the other block, so it is pushtogether.
In B, you’ll be moving the righthand
block down and away from the other block, so it is pullapart.
And in C, you’ll slide one past the other
(geologists distinguish rightlateral
and leftlateral
motion for C, but you don’t have to worry about that
much detail).
, Points Earned:, 1/1
Your Response:, C
///, 13
Points Missed, 2
Percentage, 87%
,
1., In the photo above, Dave Janesko is explaining the great Sevier Fault to Dr. Alley and the CAUSE class.
On the left, red rocks deposited in a lake extend off to Bryce National Park. On the right, black lava flows, now
cooled and hardened, are visible. The rocks meet at the Sevier Fault.
What happened here?
, A., The fault formed when a narrow crack in the Earth filled with lava that then froze.
B., The fault formed when a thin landslide during an earthquake bounced the black rocks across the red ones and
then down a cliff to lie next to the red rocks.
C., The fault marks a former valley wall. The lava flows filled the valley, so black and red rocks are now next to
each other.
D., The fault formed during Death-Valley-type spreading in the west, with the younger, black lava flows dropping
along the fault to lie next to the older, red lake sediments.
E., The fault formed when the recent push-together activity that made Death Valley also affected Utah.
The spreading that opened Death Valley affected a lot of the west, all the way over to Bryce Canyon in Utah. The
Sevier Fault, just west of Bryce, formed as pull-apart action broke the rocks, allowing younger rocks including the
black lava flow to drop down next to older rocks including the red lake sediments. There really are cases where lava
hardens in cracks, or where lava flows fill valleys, but a careful examination of the rocks here shows that the lake
sediments have not been heated by really nearby lava, so these lake sediments and the lava must have been placed
together after the lava cooled. Push-together faulting, and landslides, do occur, but not here.
, Points Earned:, 1/1
Your Response:, D
2., The processes that made Death Valley continue to operate today. For this question, ignore the sand and gravel
moved by water and wind, and think about the big motions of the rocks beneath. Choose the best answer: what are
they doing to the valley?
, A., Death Valley is getting narrower
B., Death Valley is getting wider and deeper.
C., Death Valley is getting narrower and shallower.
D., Death Valley is not changing.
E., Death Valley is getting shallower.
The pull-apart action that is spreading Death Valley and surroundings also involves uplift of mountains or downdrop
of valleys, and Death Valley has dropped as its flanking mountains have moved apart.
, Points Earned:, 1/1
Your Response:, B
3., 20-mule teams hauled borax salts out of Death Valley, and the valley still has lots of salt, sand, and river gravel in
the bottom. The most likely explanation is:
, A., Wind and rivers cut the valley deep, and after the river dried up, the river gravel, salt and sand were left behind.
B., The valley was raised by faulting, bringing up the salts, sand and gravel from subterranean caves.
C., The valley was dropped relative to the mountains by faulting, and rivers have been (and still are) carrying gravel,
sand and salts down from the mountains into the valley.
D., The valley was dropped relative to the mountains by faulting; the salts, sand and gravel had been deposited on
mountain tops by rivers and wind before the faulting started, and then were dropped down by the faulting.
E., The valley was paved with salt, sand and gravel by a movie company for a really spectacular stunt in the Dukes
of Hazzard movie, involving long-distance car chases and Daisy leaping the boys’ car across the entire park.
, Points Earned:, 0/1
Your Response:, D
4., Geophysical evidence indicates that convection is occurring in the Earth’s mantle. What is the most likely
physical explanation for why convection can occur in the mantle?
, A., The Earth’s outer core is completely melted, and this stirs the mantle to cause convection.
B., The Earth’s mantle is completely melted, and melting allows convection when heat from below causes expansion
and drop in density of the deep liquid.
C., Rocks deep in the Earth expand and so become lower in density and tend to rise as they are heated, and the deep
rocks are warm enough to flow slowly even though they are mostly solid.
D., The magnetic field lines from the rotation of the Earth’s solid inner core induce torques in the mantle, causing
convection.
E., The Earth is cooled deep inside, causing contraction that raises density, more-dense things tend to sink, and the
mantle rocks are cold enough to flow slowly even though they are not melted.
Convection seems so easy, but describing it in words is not. For “ordinary” convection, one needs something
capable of flowing (gas, liquid, or soft solid), heat below and cold above with expansion reducing density on heating
and contraction increasing density on cooling, and then a bit of time and a perturbation of some sort to get the
motion started. If you had something that expanded on cooling and contracted on heating, and you had cooling
below and warming above, you could also make convection work. The mantle is mostly solid, the outer core can’t
directly stir the mantle or cause convection, and Graham Spanier was solid and not melted the last time we checked.
, Points Earned:, 1/1
Your Response:, C
5., Heat is moved around by convection, conduction and radiation (and by lemmings carrying space heaters, if
lemmings ever carry space heaters). Which statement is more nearly correct?
, A., No matter where you are, conduction always moves heat more efficiently than does convection.
B., No matter where you are, lemmings carrying space heaters are always moving more heat than convection is
moving.
C., Convection moves heat efficiently through the space between the Sun and the Earth, but not through the soft, hot
rocks of the mantle.
D., No matter where you are, radiation always moves heat more efficiently than does convection.
E., Convection moves heat efficiently through the soft, hot rocks of the Earth’s mantle, but is not efficient at moving
heat through the space between the Sun and the Earth.
Heat from deep in the Earth is moved up through the soft bulk of the planet primarily by convection, but convection
of rocks certainly does not continue beyond the planet, where radiation becomes dominant. In the shallowest,
uppermost layers of the Earth, most of the heat transfer is by conduction. And the poor lemmings deserve a rest and
a snack.
, Points Earned:, 1/1
Your Response:, E
6., People visit Death Valley for all sorts of reasons. Some people even go there to study volcanoes. What is accurate
about those Death Valley volcanoes?
, A., The volcanoes near the edges of Death Valley produce rocks that are similar in composition to the rocks made
by volcanoes at undersea spreading ridges, because Death Valley is in many ways geologically linked to undersea
spreading ridges.
B., Death Valley has no volcanoes, and has never had volcanoes.
C., The volcanoes of Death Valley produce rocks that are similar in composition to the rocks made by volcanoes at
undersea spreading ridges, because all volcanoes make lava of the same composition.
D., Death Valley has volcanoes that are erupting as this was typed, and have been erupting continuously for decades,
so the next time you’re driving near Vegas, you can go see the lava flowing out.
E., The volcanoes of Death Valley produce rocks that are of a completely different composition than the rocks
produced by volcanoes at undersea spreading ridges, because Death Valley is geologically completely unrelated to
undersea spreading ridges.
Death Valley has spreading-ridge-type volcanoes, and if you go south from the Valley, you find the spreading ridge
in the Gulf of California; Death Valley and the Gulf of California are geologically related. There have been recent
eruptions in Death Valley (within the last centuries), but as of this writing, no volcanoes are currently erupting in
Death Valley, nor have any erupted for over a century.
, Points Earned:, 1/1
Your Response:, A
7., Dust and shells and fish poop and all sorts of things fall to the sea bed to make sediment. Across broad central
regions of the ocean, the sediment accumulates at a uniform rate—piling up about as rapidly here as it does over
there. And, in most places, the currents don’t move the sediment around much, so that it stays where it falls. Thus,
the thickness of the sediment is related to the age of the rocks beneath the sediment. If you go around an ocean and
measure the thickness of the sediment in lots of places, you are likely to find:
, A., The sediment thickness forms waves, thicker thinner thicker thinner thicker thinner, as you cross the ocean, but
with no influence from spreading ridges.
B., The sediment is thin near spreading ridges, and thicker away from the ridges.
C., The sediment is the same thickness everywhere.
D., The sediment is thick near spreading ridges, and thinner away from the ridges.
E., The sediment thickness varies a lot from place to place, but the pattern is totally random.
Sea floor is made at the spreading ridges, and moves away on both sides. Sediment piles up over time, and while
there are variations in sedimentation rate, the huge difference in age of the sea-floor rocks (140 million years near
the edges of some ocean basins, to essentially zero at the ridges) is the main controlling factor on sediment
thickness. Fish actually poop wherever they travel, and tend to go all over the oceans.
, Points Earned:, 1/1
Your Response:, B
8., Most earthquakes in the upper part of the Earth’s crust are caused by elastic rebound, according to geologists.
What do those geologists mean when they say this?
, A., All rocks on a continent move in the same direction at the same speed, even if there is a fault splitting the
continent.
B., Rocks stretched by implosion of subducted slabs then “bounce back”, shaking their surroundings.
C., Rocks moving in opposite directions on opposite sides of a fault get stuck for a while and bend, then “snap back”
when something breaks along the fault.
D., Rocks compressed by volcanic eruptions “bounce back”, shaking their surroundings.
E., High-pressure water in faults allows the rocks on opposite sides of a fault to move smoothly in opposite
directions all the time, carrying halves of houses built on the faults in opposite directions and so slowly tearing the
houses in half.
Try sliding a boulder over the ground, and you’ll find the boulder gets stuck for a while. Lean harder, the boulder
jerks forward suddenly, and you just had a tiny earthquake. Implosion earthquakes probably exist, but the rocks
don’t bounce back to their original size, and such quakes only can happen deep. We have no information on Graham
Spanier’s choice in socks, but his choice is unlikely to shake much beyond the immediate vicinity of University
Park.
, Points Earned:, 1/1
Your Response:, C
9., On the Richter scale of earthquake intensity:
, A., The ground is shaken 10 times less by a magnitude-8 quake than by a magnitude-7 quake.
B., The ground is shaken twice as much by a magnitude-8 quake as by a magnitude-4 quake.
C., The ground is shaken 10 times less by a magnitude-7 quake than by a magnitude-8 quake.
D., A magnitude-7 quake is impossible; nothing that big can occur.
E., The ground is shaken 8 times more by a magnitude-8 quake than by a magnitude-1 quake.
One problem in describing earthquakes is that the ground shaking in the smallest one you can feel is 1,000,000,000
times smaller than the ground shaking in the largest quakes. We usually dislike having a scale that requires us to talk
about an event of, say, size 100,000,000; instead, if a magnitude-1 quake moves the ground 10 units (say, 10
nanometers at some specified distance from the quake), than we say that a magnitude-2 quake moves the ground 100
units, and a magnitude-3 quake moves the ground 1000 units, and so on. You’ll notice that the magnitude is just the
number of zeros after the 1; this is a logarithmic scale.
, Points Earned:, 1/1
Your Response:, C
10., Most of the material moved by volcanoes is from the few, big ones rather then from the many, little ones. Most
of the material moved downhill in landslides is in the many, little ones rather than the few, big ones. In comparing
the importance of the few, big earthquakes to the many, little earthquakes, are earthquakes more like volcanoes (the
few big ones matter most) or like landslides (the many little ones matter most)?
, A., The many, little earthquakes matter most (like landslides).
B., All earthquakes have been retribution for the Simpsons.
C., The few, big earthquakes are just as important as the many, little earthquakes (halfway between volcanoes and
landslides).
D., Earthquakes don’t do any damage, just like volcanoes and landslides.
E., The few, big earthquakes matter most (like volcanoes).
An increase of 1 in earthquake magnitude increases ground shaking about 10-fold, increases energy release about
30-fold, and decreases frequency about 10-fold; the 30-fold increase in energy more than offsets the 10-fold
decrease in frequency of occurrence. We wish earthquakes did no damage, but the millions of people who have been
killed in earthquakes over the centuries would, if they could, testify to the damage done by earthquakes. And
historical records of earthquakes clearly preceded the Simpsons.
, Points Earned:, 1/1
Your Response:, E
11., The New Madrid Fault Zone in Missouri has had some surprisingly big earthquakes. A magneto-hydroastronomer
at a small university near the fault zone reports that the gravitational effects of the coming alignment of
several planets, together with the weakening of the magnetic field, will cause a giant earthquake on the fault zone on
Wednesday morning between 1 and 4 am. Based on materials presented in class, you would be wise to:
, A., Go to St. Louis with your camera, to photograph the Gateway Arch when it falls during the quake, because the
pictures will be worth a lot of money.
B., Invest in the Pepsi Corporation; Pepsi stocks always go up after earthquakes, and an earthquake is highly likely
at the time and place predicted.
C., Go to California to get your valuable pictures; forecasts of when earthquakes will occur are more accurate than
forecasts of where an earthquake will occur, California is more likely to have a quake, so you should be there
Wednesday to see the damage from the giant quake.
D., Listen up; although the forecast is not certain, such forecasts are usually fairly accurate and should be heeded.
E., Get back to whatever you were doing and ignore the forecast; although there might be a very small effect of
planetary gravity or magnetic fields on earthquakes, no one has ever demonstrated the ability to make such detailed
forecasts accurately, and many such forecasts have proven to be wrong.
, Points Earned:, 1/1
Your Response:, E
,
12., The picture above shows a fault in a place where mountains come down near the coast.
What likely happened to form the ramp (also called a scarp) behind the person?
, A., Pull-apart forces shoved one side up over the other, making the break.
B., Push-together forces shoved one side up over the other, making the break.
C., Slide-past forces pulled the rocks apart, making the break, and allowing one side to drop relative to the other.
D., Slide-past forces shoved one side up over the other, making the break.
E., Pull-apart forces pulled the rocks apart, making the break, and allowing one side to drop relative to the other.
The down-side dropped along the ramp compared to the up-side. (This is actually an interesting one; it formed in
Alaska during the 1964 earthquake. That was a push-together quake, but it was so huge and moved so much rock in
different directions that some of the rock ended up having pull-apart motions, such as this one.)
, Points Earned:, 1/1
Your Response:, E
13., The Earth includes:
, A., A solid inner core, a liquid outer core, and a mantle with a liquid asthenosphere.
B., A solid inner core, a liquid outer core, and a mantle with a little liquid in a mostly solid asthenosphere.
C., A liquid inner core, a solid outer core, and a mantle with a little liquid in a mostly solid asthenosphere.
D., A Pepsi inner core, a Coke outer core, and a mantle of Gatorade drinkers.
E., A liquid inner core, a solid outer core, and a mantle with a liquid asthenosphere.
High pressure stabilizes solid in the inner core, but the slightly lower pressure on the outer core allows the iron there
to be melted. The iron-silicate mantle is mostly solid, but a bit of melt occurs in the asthenosphere. And the great
heat of the core would break down both natural and artificial sweeteners, so cola cannot be found there.
, Points Earned:, 0/1
Your Response:, A
14., What is accurate about seismic waves moving through the Earth?
, A., Neither s-waves (also called shear-waves) nor p-waves (also called push-waves or sound waves) move through
liquids.
B., S-waves (also called push-waves or sound waves) move through all liquids except Diet Pepsi, and p-waves (also
called shear-waves) move through no liquids except Diet Pepsi.
C., Neither s-waves (also called shear-waves) nor p-waves (also called push-waves or sound waves) move through
solids.
D., S-waves (also called shear-waves) and p-waves (also called push-waves or sound waves) both move through
liquids.
E., P-waves (also called push-waves or sound waves) move through liquids and solids, whereas s-waves (also called
shear waves) move through solids but not liquids.
P-waves go through liquids and solids, because you can squeeze and release a liquid or a solid—push hear and it
squeezes a bit, which squeezes what is next to you… and on in a wave. S-waves are a bit like waves on a rope—grab
an end and move it sideways, which moves the neighboring part sideways… This works with solids, but not liquids,
which cannot “grab” and move the neighboring part.
, Points Earned:, 1/1
Your Response:, E
,
15., The above diagram is from one of the Geomations in the unit. It shows three possible fault styles. A and B are
cross-sections, with a collapsed building on top to show you which way is up—the yellow band is a distinctive layer
of rock that was broken by the earthquake that also knocked down the building. C is viewed from a helicopter,
looking down on a road with a dashed yellow line down the middle; the road was broken by an earthquake along the
green fault, and the earthquake knocked down a building to make the funky-looking brown pile in the upper right.
What is accurate about the different earthquake styles?
, A., B is pull-apart, C is slide-past, and A is push-together.
B., B is pull-apart, C is push-together, and A is slide-past.
C., B is slide-past, C is push-together, and A is pull-apart.
D., B is push-together, C is pull-apart, and A is slide-past.
E., B is push-together, C is slide-past, and A is pull-apart.
Imagine putting the image on paper, cutting out the blocks (one block on each side of the fault), and then sliding
them back together to make the original, unbroken features. A and B stand up from the table, C lies down on the
table. Now, slide them to make the picture as seen here. In A, you’ll be moving the right-hand block up and toward
the other block, so it is push-together. In B, you’ll be moving the right-hand block down and away from the other
block, so it is pull-apart. And in C, you’ll slide one past the other (geologists distinguish right-lateral and left-lateral
motion for C, but you don’t have to worry about that much detail).
, Points Earned:, 1/1
Your Response:, A
Your response has been submitted successfully.
///, 15
Points Missed, 0
Percentage, 100%
,
1., Dave Janesko is explaining the great Sevier Fault to Dr. Alley and the CAUSE class.
Dave has just informed everyone that the black rocks, which formed by cooling of a very hot lava flow, are
much younger than the red rocks, which formed from sediments deposited in a lake. He has examined the
red rocks and found that they have not been “cooked” by heat from the black rocks, so the red and black
rocks must have been placed together after the black rocks cooled. And, he has examined the contact
between red and black rocks and found that it is a fault that has been scratched by the motion of the rocks
along the fault. It is likely that:
, A., The scratches are nearly vertical, because the black rocks were dropped down along a pullapart
fault to lie next to the red rock.
B., The scratches are all horizontal, because the red rocks moved over the black rocks in a landslide.
C., The scratches make little curlicues, because motion on the fault screwed the two sides together.
D., The scratches are nearly horizontal, because the black rocks were slid in from the side along a slidepast
fault.
E., The scratches are nearly vertical, because the black rocks were pushed up from below along a pushtogether
fault to lie next to the red rocks.
The spreading that opened Death Valley affected a lot of the west, all the way over to Bryce Canyon in
Utah. The Sevier Fault, just west of Bryce, formed as pullapart
action broke the rocks, allowing younger
rocks including the black lava flow to drop down next to older rocks including the red lake sediments. The
scratches are not too far from vertical, made as the rocks dropped down.
, Points Earned:, 1/1
Your Response:, A
2., The processes that made Death Valley have been operating for millions of years, and continue to
operate today. For this question, ignore the sand and gravel moved by water and wind, and think about
the big motions of the rocks beneath. If you had visited Death Valley 1 million years ago, you would have
found the valley then to have been (choose the best answer):
, A., Wider and deeper than it is today.
B., Narrower than it is today.
C., Shallower than it is today.
D., Narrower and shallower than it is today.
E., The same as it is today.
The pullapart
action that is spreading Death Valley and surroundings also involves uplift of mountains or
downdrop of valleys, and Death Valley has dropped as its flanking mountains have moved apart. Thus, in
the past the valley was narrower and shallower than it is now, and the motions have deepened and
widened the valley.
, Points Earned:, 1/1
Your Response:, D
,
3., The picture above shows river gravels in the bottom of Death Valley.
Based on the lesson materials for this unit, a likely explanation for this occurrence of river gravels in the
valley bottom is:
, A., The valley was raised by faulting, bringing up gravels from subterranean caves.
B., The valley was dropped relative to the mountains by faulting, and rivers now are carrying gravels down
from the mountains into the valley.
C., The valley was dropped relative to the mountains by faulting; these gravels had been deposited on
mountain tops by rivers before the faulting started, and then the gravels were dropped down by the
faulting.
D., The valley was paved with gravels by a movie company for a really spectacular stunt in the Dukes of
Hazzard movie, involving longdistance
car chases and Daisy leaping the boys’ car across the entire park.
E., The valley is deep because it was carved by a river, which later dried up when the desert formed,
leaving the gravels behind.
Faulting dropped the valley (or raised the mountains, or more likely both), and the melting snows of the
mountains feed rivers that carry rocks down into the valley, slowly filling it up while lowering the
mountains. There really are deep canyons that were carved by rivers, but as we saw in class and online,
Death Valley is not one of them. Rivers don’t run on the tops of mountains to deposit gravels. And Daisy
was more into shorts than into long jumps.
, Points Earned:, 1/1
Your Response:, B
4., We believe that convection occurs in the Earth’s mantle because:
, A., The Earth is heated deep inside, causing expansion that reduces density, lessdense
things tend to
rise, and the mantle rocks are hot enough to flow slowly even though they are not melted.
B., The Earth’s outer core is completely melted, and this stirs the mantle to cause convection.
C., Graham Spanier is completely melted, and he drives convection in the mantle.
D., The Earth is cooled deep inside, causing contraction that raises density, moredense
things tend to
sink, and the mantle rocks are cold enough to flow slowly even though they are not melted.
E., The Earth’s mantle is completely melted, and melting allows convection.
Convection seems so easy, but describing it in words is not. For “ordinary” convection, one needs
something capable of flowing (gas, liquid, or soft solid), heat below and cold above with expansion
reducing density on heating and contraction increasing density on cooling, and then a bit of time and a
perturbation of some sort to get the motion started. If you had something that expanded on cooling and
contracted on heating, and you had cooling below and warming above, you could also make convection
work. The mantle is mostly solid, the outer core can’t directly stir the mantle or cause convection, and
Graham Spanier was solid and not melted the last time we checked.
, Points Earned:, 1/1
Your Response:, A
5., Heat transfer by convection is:
, A., Always more efficient than heat transfer by radiation.
B., Always less efficient than heat transfer by lemmings.
C., Always more efficient than heat transfer by conduction.
D., Efficient through hot, soft rocks but inefficient through space.
E., Efficient through space but inefficient through hot, soft rocks.
Heat from deep in the Earth is moved up through the soft bulk of the planet primarily by convection, but
convection of rocks certainly does not continue beyond the planet, where radiation becomes dominant. In
the shallowest, uppermost layers of the Earth, most of the heat transfer is by conduction. And the poor
lemmings deserve a rest and a snack.
, Points Earned:, 1/1
Your Response:, D
6., Volcanoes in Death Valley:
, A., Are erupting all the time, so you can drive out from Vegas and be sure to see a few in action.
B., Produce rocks with similar composition to the rocks made at undersea spreading ridges, because
Death Valley is geologically related to spreading ridges.
C., Do not exist, and have never existed.
D., Produce rocks of composition completely unlike rocks of undersea spreading ridges, because Death
Valley has no geological similarities to undersea spreading ridges.
E., Produce rocks with similar compositions to those of undersea spreading ridges, because all volcanoes
produce rocks of the same composition.
Death Valley has spreadingridgetype
volcanoes, and if you go south from the Valley, you find the
spreading ridge in the Gulf of California; Death Valley and the Gulf of California are geologically related.
There have been recent eruptions in Death Valley (within the last centuries), but as of this writing, no
volcanoes are currently erupting in Death Valley, nor have any erupted for over a century.
, Points Earned:, 1/1
Your Response:, B
7., Geologists got their shorts tied in knots because they (the geologists, not the shorts or the knots) were
so excited when they discovered what about the pattern of sediment thickness across undersea spreading
ridges:
, A., The sediment is the same thickness everywhere, showing that the rocks are all about the same age
and accumulate sediment at the same rate everywhere.
B., The sediment is thick near the ridges, and thins as you go away from the ridges, because fish always
poop over the ridges.
C., The sediment is thick near the ridges, and thins as you go away from the ridges, because the rocks
near the ridges are oldest and have had the most time to accumulate sediment, whereas rocks farther
away are younger and have not had as long to accumulate sediment.
D., The sediment is thin near the ridges, and thickens as you go away from the ridges, because the rocks
near the ridges are young and have had little time to accumulate sediment, whereas rocks farther away
are older and have had longer to accumulate sediment.
E., The sediment is thin near the ridges, and thickens as you go away from the ridges, because fish don’t
poop over the ridges.
Sea floor is made at the spreading ridges, and moves away on both sides. Sediment piles up over time,
and while there are variations in sedimentation rate, the huge difference in age of the seafloor
rocks (140
million years near the edges of some ocean basins, to essentially zero at the ridges) is the main
controlling factor on sediment thickness. Fish actually poop wherever they travel, and tend to go all over
the oceans.
, Points Earned:, 1/1
Your Response:, D
8., When discussing earthquakes that happen in the upper part of the Earth’s crust, geologists believe
that most are caused by elastic rebound. This means:
, A., Rocks taken down into the Earth by subduction are squeezed until they implode, and then they
elastically rebound to their former size, shaking their surroundings.
B., Rocks on opposite sides of a break, or fault, move in opposite directions, and move freely all the time
because highpressure
groundwater lubricates motion.
C., Rocks on opposite sides of a break, or fault, move in opposite directions, get stuck against each other
for a while, bend, then “snap back” when something breaks or gives along the fault.
D., Rocks on opposite sides of a break, or fault, move in the same direction at the same speed.
E., Graham Spanier wears support hose.
Try sliding a boulder over the ground, and you’ll find the boulder gets stuck for a while. Lean harder, the
boulder jerks forward suddenly, and you just had a tiny earthquake. Implosion earthquakes probably exist,
but the rocks don’t bounce back to their original size, and such quakes only can happen deep. We have
no information on Graham Spanier’s choice in socks, but his choice is unlikely to shake much beyond the
immediate vicinity of University Park.
, Points Earned:, 1/1
Your Response:, C
9., On the Richter scale of earthquake intensity:
, A., The ground is shaken twice as much by a magnitude5
quake as by a magnitude2.5
quake.
B., The ground is shaken 10 times less by a magnitude4
quake than by a magnitude5
quake.
C., The ground is shaken 10 times less by a magnitude3
quake than by a magnitude2
quake.
D., The ground is shaken 3 times more by a magnitude3
quake than by a magnitude1
quake.
E., A magnitude8.5
quake is impossible; nothing that big can occur.
One problem in describing earthquakes is that the ground shaking in the smallest one you can feel is
1,000,000,000 times smaller than the ground shaking in the largest quakes. We usually dislike having a
scale that requires us to talk about an event of, say, size 100,000,000; instead, if a magnitude1
quake
moves the ground 10 units (say, 10 nanometers at some specified distance from the quake), than we say
that a magnitude2
quake moves the ground 100 units, and a magnitude3
quake moves the ground 1000
units, and so on. You’ll notice that the magnitude is just the number of zeros after the 1; this is a
logarithmic scale.
, Points Earned:, 1/1
Your Response:, B
10., Most of the material moved by volcanoes is from the few, big ones rather then from the many, little
ones. Most of the material moved downhill in landslides is in the many, little ones rather than the few, big
ones. In comparing the importance of the few, big earthquakes to the many, little earthquakes, are
earthquakes more like volcanoes (the few big ones matter most) or like landslides (the many little ones
matter most)?
, A., Earthquakes don’t do any damage, just like volcanoes and landslides.
B., The few, big earthquakes are just as important as the many, little earthquakes (halfway between
volcanoes and landslides).
C., The many, little earthquakes matter most (like landslides).
D., All earthquakes have been retribution for the Simpsons.
E., The few, big earthquakes matter most (like volcanoes).
An increase of 1 in earthquake magnitude increases ground shaking about 10fold,
increases energy
release about 30fold,
and decreases frequency about 10fold;
the 30fold
increase in energy more than
offsets the 10fold
decrease in frequency of occurrence. We wish earthquakes did no damage, but the
millions of people who have been killed in earthquakes over the centuries would, if they could, testify to
the damage done by earthquakes. And historical records of earthquakes clearly preceded the Simpsons.
, Points Earned:, 1/1
Your Response:, E
11., You hear an astronomer on the evening news, pointing out a coming alignment of planets and
predicting that the extra gravitational attraction is sure to trigger a huge earthquake in California during the
few hours of alignment. Based on what you learned in class, a reasonable approach is to:
, A., Take it seriously; maybe the quake isn’t certain, but a big quake is much more likely than not during
those few hours.
B., Go to California with your camera to take pictures of the buildings falling down during the alignment so
you can sell the pictures for lots of money.
C., Ignore it; although gravitational forces such as tides and planetary pulls might possibly exert a very
small effect on earthquakes, no one has successfully predicted the whereandwhen
of earthquakes.
D., Stay the heck out of California, because if you go, you will be trampled to death by all the scientists
running to California to observe the quake.
E., Invest in the Pepsi Corporation; Pepsi stocks always go up after earthquakes, and an earthquake is
highly likely at the time and place predicted.
By keeping track of where earthquakes happen, combing written and oral histories of past earthquakes,
looking at geological deposits to see where shaking has occurred and broken rocks or tree roots or
caused sand boils, and measuring where rocks are moving and where they aren’t, good estimates can be
made of earthquake hazards; but, we can’t figure out exactly when the next quake will hit. Planetaryalignment
predictions have been made, and have failed miserably. The tiny effect of gravity of the planets
on the Earth has not been shown to affect earthquakes at all, although it remains possible that some very
small influence exists.
, Points Earned:, 1/1
Your Response:, C
,
12., The picture above shows a view in the Earthquake Lake region just northwest of Yellowstone.
The ramp or slope (often called a scarp) formed in an earthquake.What likely happened?
, A., Pullapart
forces pulled the rocks apart, making the break, and allowing one side to drop relative to
the other.
B., Pullapart
forces shoved one side up over the other, making the break.
C., Slidepast
forces shoved one side up over the other, making the break.
D., Slidepast
forces pulled the rocks apart, making the break, and allowing one side to drop relative to
the other.
E., Pushtogether
forces shoved one side up over the other, making the break.
The pullapart
forces west of Yellowstone are similar to those of Death Valley, and may be responding to
the same broad spreading of the west that widens Death Valley. The two sides moved apart, and then one
side dropped relative to the other.
, Points Earned:, 1/1
Your Response:, A
13., The Earth includes:
, A., A breaksratherthanflows
lithosphere, a flowsratherthanbreaks
asthenosphere, and a solid inner
core.
B., A Coke inner core, a Pepsi outer core, and a mantle of Bart Simpson Burger King glasses.
C., A breaksratherthanflows
asthenosphere, and a solid outer core.
D., A solid inner core in direct contact with a liquid asthenosphere.
E., A liquid asthenosphere, a solid mantle, and a watery hydrosphere.
High pressure stabilizes solid in the inner core, but the slightly lower pressure on the outer core allows the
iron there to be melted. The ironsilicate
mantle is mostly solid, but a bit of melt occurs in the
asthenosphere. The uppermost part of the mantle and the crust are cold enough to break rather than
flowing. And the great heat of the core would break down both natural and artificial sweeteners, so cola
cannot be found there.
, Points Earned:, 1/1
Your Response:, A
14., What is accurate about seismic waves moving through the Earth?
, A., Swaves
(also called shearwaves)
move through neither solids nor liquids.
B., Swaves
(also called shearwaves)
move through both solids and liquids.
C., Swaves
(also called shearwaves)
move through solids but not liquids.
D., Swaves
(also called shearwaves)
move through liquids but not solids.
E., Swaves
(also called shearwaves)
move through solids and all liquids except Diet Pepsi.
Swaves
are a bit like waves on a rope—grab an end and move it sideways, which moves the neighboring
part sideways… This works with solids, but not liquids, which cannot “grab” and move the neighboring
part.
, Points Earned:, 1/1
Your Response:, C
,
15., The above diagram is from one of the Geomations in the unit. It shows three possible fault styles. A
and B are crosssections,
with a collapsed building on top to show you which way is up—the yellow band
is a distinctive layer of rock that was broken by the earthquake that also knocked down the building. C is
viewed from a helicopter, looking down on a road with a dashed yellow line down the middle; the road was
broken by an earthquake along the green fault, and the earthquake knocked down a building to make the
funkylooking
brown pile in the upper right. What is accurate about the different earthquake styles?
, A., C is pushtogether,
B is slidepast,
and A is pullapart.
B., C is slidepast,
B is pushtogether,
and A is pullapart.
C., C is slidepast,
B is pullapart,
and A is pushtogether.
D., C is pushtogether,
B is pullapart,
and A is slidepast.
E., C is pullapart,
B is pushtogether,
and A is slidepast.
Imagine putting the image on paper, cutting out the blocks (one block on each side of the fault), and then
sliding them back together to make the original, unbroken features. A and B stand up from the table, C
lies down on the table. Now, slide them to make the picture as seen here. In A, you’ll be moving the righthand
block up and toward the other block, so it is pushtogether.
In B, you’ll be moving the righthand
block down and away from the other block, so it is pullapart.
And in C, you’ll slide one past the other
(geologists distinguish rightlateral
and leftlateral
motion for C, but you don’t have to worry about that
much detail).
, Points Earned:, 1/1
Your Response:, C
——————————————————————————————————————————————–
Practice Quiz #3
Your response has been submitted successfully.
///, 0
Points Missed, 5
Percentage, 0%
1., Hawaiian volcanoes, where they emerge above sea level, are:
, A., Especially silicarich.
B., All clinkerylooking
lava called aa.
C., Broad, gentle shield volcanoes.
D., All ropylooking
lava called pahoehoe.
E., Steep, narrow stratovolcanoes.
The lowsilica
lava from the Hawaiian hot spot flows easily, so the lava spreads out to make broad, gentle
volcanoes that look like shields of medieval warriors. Some Hawaiian lava is clinkery aa (pronounced “ahah”),
but some is ropy pahoehoe (pronounced “pa hoe ee hoe ee”), controlled by subtle differences in temperature,
composition, etc.
, Points Earned:, 0/1
Correct Answer:, C
Your Response:, E
2., Old, cold ocean floor sinks at subduction zones. Why does this cause melting to feed volcanoes?
, A., Subduction zones weaken the mantle so that convection cells from the deep mantle can rise along the
downgoing slabs.
B., Subduction zones weaken the mantle so that hot spots can rise along the downgoing slabs.
C., Water taken down subduction zones lowers the melting temperature in and near the slabs.
D., Sediments scraped off downgoing slabs pile up, as at Olympic, trapping the Earth’s heat beneath and
causing the rocks below to be warmer than elsewhere in the mantle.
E., Slabs quickly become the hottest things in the mantle because of friction from the subduction.
Throw a little dry flour in a warm oven, and not much happens. Add some water, or better, some water and
some carbon dioxide from yeast, and things happen in a hurry. The subduction zone takes water, and carbon
dioxide in shells and other things, down to lower the melting point and feed volcanoes. Friction does warm the
downgoing
slabs, but slabs start off way colder than the rocks into which they move, and remain colder for a
while. Sliding your cold feet along the sheets when you get into bed on a winter night may warm your toes a
little by friction, but if you happen to share the bed with a significant other, putting your tootsies on that persons
bare belly will tell you that frictional heating takes a while! The scrapedoff
pile of sediment traps a tiny bit of
heat, but not too much; the downgoing slab makes the nearby mantle colder than normal, not warmer. And
nature tends to separate regions where something is flowing one way from regions where the flow is reversed;
if the flows are too close together, one will drag the other along and change its direction. Hot spots occasionally
ride along on spreading ridges, because both involve rising, but not on subduction zones.
, Points Earned:, 0/1
Correct Answer:, C
Your Response:, D
3., Which of the following is commonly expected near a “textbook” subduction zone (that is, near a subduction
zone that is so perfect and free of confusing complications that you would use it in a textbook to teach
students)?
, A., Basaltic midoceanridgetype
volcanoes.
B., Andesitic stratovolcanoes
C., Slidepast
(or transform, with horizontal but not vertical movement) earthquakes and faults.
D., Pullapart
earthquakes and faults.
E., Basaltic hotspottype
volcanoes.
Pullapart
earthquakes and faults often occur at pullapart
basaltic midocean
ridges, which are not subduction
zones. Slidepast
also occurs on the planet, but not primarily at subduction zones, which also are not hot spots.
But subduction does lead to layered thicklavaflow/
blownupbits
stratovolcanoes of andesitic composition.
, Points Earned:, 0/1
Correct Answer:, B
Your Response:, D
4., Which of the following is commonly expected near a “textbook” subduction zone (that is, near a subduction
zone that is so perfect and free of confusing complications that you would use it in a textbook to teach
students)?
, A., Slidepast
(or transform, with horizontal but not vertical movement) earthquakes and faults.
B., Piledup
mud and other things scraped off the descending slab.
C., Basaltic midoceanridgetype
volcanoes.
D., Pullapart
earthquakes and faults.
E., Basaltic hotspottype
volcanoes.
Pullapart
earthquakes and faults often occur at pullapart
basaltic midocean
ridges, which are not subduction
zones. Slidepast
also occurs on the planet, but not primarily at subduction zones, which also are not hot spots.
But subduction does lead to scraping of mud off the descending slabs, making piles such as the Olympic
Peninsula.
, Points Earned:, 0/1
Correct Answer:, B
Your Response:, C
5., The volcanoes of the island of Hawaii eventually will:
, A., Blow up as powerfully as the main 1980 eruption of Mt. St. Helens.
B., Last forever while nothing happens to them except for development of a protective layer of condominiums.
C., Drift off the hot spot and cease to erupt, while a new volcano grows to their southeast.
D., Rise above sea level as they cool and sink, and are eroded.
E., Blow up as powerfully as the main eruptions of Yellowstone, 1000 times bigger than Mt. St. Helens.
As they drift off the hot spot, the Hawaiian chain volcanoes lose their source of melt and quit erupting. But, a
new volcano grows. Indeed, the new one, Loihi Seamount, is already there and erupting underwater, building
toward the surface. As they cool and sink, and are eroded, the Hawaiian volcanoes disappear below sea level.
Hawaiian volcanoes are “friendly”, not having highly explosive eruptions. Yellowstone is an anomaly; the hot
spot is not making a huge amount of melt, and that melt is modified in coming through the continent, so
Yellowstone explodes despite being a hot spot. But most hotspot
volcanoes are not highly explosive. The
“protective” layer of condominiums is developing in parts of Hawaii, but lots will happen to the volcanoes in
addition—earthquakes and eruptions and drifting and more—and wait until next time when we learn about
sides falling off!
, Points Earned:, 0/1
Correct Answer:, C
Your Response:, D
Rock On #3
Your response has been submitted successfully.
///, 13
Points Missed, 2
Percentage, 87%
1., Which of the following is commonly expected near a “textbook” subduction zone (that is, near a subduction
zone that is so perfect and free of confusing complications that you would use it in a textbook to teach
students)?
, A., Andesitic stratovolcanoes, such as Mt. St. Helens.
B., Basaltic hotspottype
volcanoes, such as at Hawaii Volcanoes.
C., Basaltic midoceanridgetype
volcanoes, such as are found at undersea spreading ridges.
D., Slidepast
(or transform, with horizontal but not vertical movement) earthquakes and faults, such as occur
along the San Andreas Fault.
E., Pullapart
earthquakes and faults, such as occur in Death Valley.
Pullapart
earthquakes and faults often occur at pullapart
basaltic midocean
ridges, which are not subduction
zones. Slidepast
also occurs on the planet, but not primarily at subduction zones, which also are not hot spots.
But subduction does lead to layered thicklavaflow/
blownupbits
stratovolcanoes of andesitic composition.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
2., Melting happens in association with a subduction zone. What is going on to cause this?
, A., The motion of the downgoing slab weakens the mantle so that a hot spot from deep below can rise along
the downgoing slab and cause melting.
B., The immense friction between the downgoing slab and the overlying rocks makes the slab the hottest things
in the mantle, causing much melting nearby.
C., The bending and friction associated with scraping off a pile of sediment, such as the Olympic Peninsula,
makes the pile very hot, and the downgoing slab passes through the hot zone and melts in response.
D., The downgoing slab takes along water, and that water lowers the temperature at which rock melts to allow
melting in and near the slab.
E., The scrapedoff
pile from the subduction zone traps the Earth’s heat beneath, and the downgoing slab
passes through this hot zone and melts in response.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
,
3., The picture shows some rocks on the beach at Olympic National Park. The pocket knife is about 3 inches
(or 8 cm) long. What is the story of these rocks?
, A., The pocket knife washed overboard from a Chinese freighter in a storm, and floated to the beach on the
currents; scientists use the distribution of such flotsam and jetsam to learn about the oceanic currents that drive
plate tectonics.
B., Earthquakes knocked loose undersea muds that raced down the slope into the subduction zone to make
these layered rocks, which were scraped off the downgoing slab, part of the process by which continents shrink
as material is scraped off their edges at subduction zones.
C., The pocket knife was flushed out of an airline toilet by an absentminded
geologist, and fell on the rock.
D., Earthquakes knocked loose undersea muds that raced down the slope into the subduction zone to make
these layered rocks, which were scraped off the downgoing slab, part of the process by which continents grow
as material is added to their edges at subduction zones.
E., The layering comes from different volcanic eruptions that piled material on the beach, as part of the process
by which spreading zones tear apart continents, causing them to become smaller over time.
Olympic is the pile of scrapedoff
stuff, and some of it fell into the trench rather recently during earthquakes.
Buildup
of material above subduction zones contributes to growth of continents over time, not shrinkage. There
really are volcanic layers, but as described in the slide show, these are not volcanic layers, and continents grow
over time rather than shrinking. Things do wash off freighters, and items such as rubber ducks and shoes have
been used to trace ocean currents, but pocket knives sink, and ocean currents are not the driving force for
drifting plates. Airline toilets flush into holding tanks on the plane, not onto people or rocks below, and very
rarely have pocket knives because the knives are confiscated first.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
4., Subduction zones produce an amazing variety of geological features. These include:
, A., Deep trenches in the sea floor, which are old river valleys eroded by the vigorous streams flowing down
from the mountains.
B., Deep trenches in the sea floor, formed by the bending of the downgoing plate, and sometimes filled with sea
water but sometimes filled with sediment eroded from nearby land.
C., Deep trenches in the sea floor, which are really fjords eroded by glaciers flowing down from the mountains
and away from the coast out to sea.
D., Deep trenches in the sea floor, formed by the bending of the downgoing plate, but filled with basaltic lava
flows from the hot spots that feed the subductionzone
volcanoes.
E., Deep trenches in the sea floor, formed by the weight of discarded Microsoft Windows CDs and Starbucks
coffee cups, heaved into the ocean from Seattle by angry consumers.
The deepest spots in the ocean are formed when downgoing slabs are bent downward to make deep trenches
parallel to the shore. However, sometimes these trenches become sedimentfilled.
Microsoft CDs are a
relatively small part of that sediment. Rivers don’t cut below sea level, and glaciers flowing away from the coast
cannot cut a huge trench parallel to the coast.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
5., You use highly accurate techniques to learn the time when lots and lots of different volcanic rocks solidified
from melted rock. You do this for many different rocks across the continents, and many different rocks across
the sea floor. You will find that (note that “older” rocks are those that solidified more years ago, and “younger”
rocks are those that solidified fewer years ago.):
, A., The seafloor
rocks and the continental rocks are typically of about the same age.
B., The seafloor
rocks are typically younger than the continental rocks, because some of the older continental
rocks were blasted away by the collision that made the moon, revealing the younger seafloor
rocks beneath.
C., The seafloor
rocks are typically younger than the continental rocks, because seafloor
rocks are taken back
into the mantle at subduction zones about as rapidly as new seafloor
rocks are produced, while continental
rocks are not taken back into the mantle at subduction zones.
D., The seafloor
rocks are typically older than the continental rocks, because the seafloor
rocks formed first
and then they were melted to make the continental rocks.
E., The seafloor
rocks are typically older than the continental rocks, because the seafloor
rocks formed first
and then the continental rocks fell on top of them as the planet grew.
You can find young rocks on the sea floor and on the continents, but all of the old rocks on the planet are on
continents—there are no old seafloor
rocks. The older sea floor has all been recycled at subduction zones.
, Points Earned:, 0/1
Correct Answer:, C
Your Response:, A
6., Volcanoes of many different types can be observed at the surface of the Earth. Suppose you are looking at
a hotspot
volcano. If you could see deep beneath that volcano, what would you find?
, A., A rising tower of hot rock, coming up from below and perhaps from waaaaay below, down at the bottom of
the mantle.
B., A Pepsi machine, that has been shaken by earthquakes so that the bottles are exploding.
C., A volcanicarcproducing,
RingofFire
type subduction zone.
D., A scrapedoff
pile of material, heated by the offscraping
and melting in the middle to feed the volcano.
E., A seafloorproducing
spreading ridge.
Earthquakes make sound waves that go through the whole Earth, and go slower through hotter, lessdense
rocks. By setting out listening devices called seismometers around the Earth, and listening to the waves from
many earthquakes in many places, scientists can map the hotter regions, and find that towers of hot rock come
up from way deep in the Earth in some places. But, some other hot spots, while clearly coming up from below,
don’t seem to start quite as deep.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
7., What is accurate about a typical volcano formed by eruptions from a hot spot?
, A., The lava of the volcano is andesitic in composition, and the volcano itself is shaped like a Pepsi can, with
vertical sides below sea level.
B., The lava of the volcano is mostly andesitic in composition, and the volcano itself has steep sides where
projecting above sea level, but lesssteep
sides on undersea portions.
C., The lava of the volcano contains less silica than basalt has, and thus is like the mantle in composition
because the melt comes from the mantle, and the volcano itself has uniformly sloping sides like the beautiful
peak of Mt. St. Helens before the 1980 eruption.
D., The lava of the volcano is mostly basaltic in composition, with gradual sides where the volcano projects
above sea level, but steeper sides on undersea portions.
E., The lava of the volcano is mostly andesitic in composition, with gradual sides where the volcano projects
above sea level, but steeper sides on undersea portions.
The rising hot rock of hot spots feeds volcanoes. Both sea floor and hotspot
volcanoes come from melting a
little of the verylowsilica
mantle, pulling out the melt, and freezing it, and so are basaltic (lowsilica)
volcanoes.
Note, though, that a few hotspots (such as Yellowstone) are not basaltic, because the basalt has been altered
in getting through the continent. The melt probably started out as something that would make basalt, and
indeed, the Yellowstone hotspot
track includes basaltic lavas such as those at the glorious Craters of the Moon
National Monument. The hotspot
lavas are runny, and spread easily under the air to make volcanoes with
gradual slopes, unlike the steep stratovolcanoes, although the slopes of hotspot
volcanoes are steeper under
water because the water cools the lava so rapidly that it can’t spread far.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
,
8., Look at the picture above. What happened here?
, A., An immense marmot named George, shown here, dug the hole.
B., A sharp bend in a river created a whirlpool that carved the hole now filled by a lake.
C., A great volcanic explosion occurred, spreading material across the landscape and leaving a hole.
D., DeathValleytype
faulting dropped the bottom, making space for the lake; during the Ice Age, Death Valley
looked like this, too.
E., A giant glacier used to sit here, and water flowing into a hole on the surface fell to the bed and hollowed out
a great pothole, seen here.
Nature has many ways to make holes, and many other ways to make mountains. Part of this class is learning to
read the clues, just as geologists do. We saw at Death Valley that the faults tend to make straight lines.
Streams on glaciers are not nearly this big, nor are river bends. And while George is cute, he could never dig
such a hole. This is the aftermath of the eruption of Mt. St. Helens.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
9., Major differences between Mt. St. Helens and Hawaiian volcanoes include:
, A., Mt. St. Helens is a lowsilica,
quietly erupting shield volcano, and Hawaii has mediumtohighsilica,
explosively erupting stratovolcanoes.
B., Mt. St. Helens is a mediumtohighsilica,
explosively erupting stratovolcano, and Hawaii has lowsilica,
quietly erupting shield volcanoes.
C., Mt. St. Helens is a volcano, but Hawaii doesn’t have any volcanoes, and never has.
D., Mt. St. Helens is a lowsilica,
explosively erupting stratovolcano, and Hawaii has mediumtohighsilica,
quietly erupting shield volcanoes.
E., Mt. St. Helens is a mediumtohighsilica,
quietly erupting shield volcano, and Hawaii has lowsilica,
explosively erupting stratovolcanoes.
The lowsilica
lava from the Hawaiian hot spot flows easily without large explosions, so the lava spreads out to
make broad, gentle volcanoes that look like shields of medieval warriors. Melt a little basaltic sea floor with
some water and sediment, and you get silicarich
andesite feeding explosive, subductionzone
stratovolcanoes
such as Mt. St. Helens. Hot spots and spreading ridges make lowsilica,
basaltic volcanoes, which don’t
explode powerfully. Mt. St. Helens is a stratovolcano, but stratovolcanoes are steep, not broad and flat. Mt. St.
Helens was the most active of the Cascades volcanoes even before its big 1980 eruption, and the volcano has
erupted many times since the big eruption.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
10., You get in your Magic School Bus, drive down the throat of a volcano, and find that you are driving through
melted rock that flows with much greater difficulty than does most melted rock, because the melted rock you
are driving through is lumpier than typical for melted rock. It is likely that the melted rock you are driving through
is:
, A., Especially rich in water and carbon dioxide compared to most melted rocks.
B., Especially low in water and carbon dioxide compared to most melted rocks.
C., Especially rich in Diet Pepsi compared to most melted rocks.
D., Especially warm compared to most melted rocks.
E., Especially rich in iron and other things that would get between siliconoxygen
tetrahedra, compared to most
melted rocks.
The siliconoxygen
tetrahedra link up to make lumps, so anything that gets in the way of this linking will oppose
lumping. Iron, water, carbon dioxide, or high heat that shakes the lumps apart can all oppose the lumping of
polymerization. Diet Pepsi would break up lumps, too, although isn’t especially likely in melted rock.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
,
11., These two pictures are from Hawaii Volcanoes National Park, on the flanks of Kilauea Volcano. How are
pictures I and II related?
, A., Lava flows chill on top and sides while the unchilled central part continues flowing as shown in II, and if
more lava is not supplied to keep the tubes filled, the tubes may drain to leave caves, such as the one shown in
I.
B., Lava flows chill on top and sides while the unchilled central part continues flowing as shown in II, and later
after the central part chills too, it is dissolved more easily by acidic groundwaters because it froze later, leaving
caves such as the one shown in I.
C., Lava flows chill on top and sides while the unchilled central part continues flowing as shown in II, and later
after the central part chills too, it is mined out by the Park Service because it is softer, making visitorentertaining
caves, such as the one shown in I.
D., Subduction processes open tubes such as shown in I, and then later when volcanic eruptions happen, the
lava uses those tubes as shortcuts to the sea, as shown in II.
E., Earthquakes open tubes such as shown in I, and then later when volcanic eruptions happen, the lava uses
those tubes as shortcuts to the sea, as shown in II.
2000degree
lava hits 70degree
air on top and sides, and 70degree
rock on the bottom, when the lava first
flows out of the volcano, so the lava tends to freeze on all sides. Often, though, the lava will flow downhill away
from the volcano fast enough that the leading edge will break as rapidly as it chills, and thus the end won’t get
plugged, allowing the sort of lava flow seen in II. Stop the supply of melted rock to the volcano end of the tube,
the tube drains out, and a cave is left, such as the beautiful one seen in II.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
12., Earthquakes can be caused in many different ways. The best interpretation of the planet’s earthquakes is
that:
, A., The rare, deepest ones are caused by “implosion” as minerals in downgoing slabs of subduction zones
suddenly switch to a denser arrangement, whereas common shallower ones are caused by elastic rebound of
bent rocks when a fault breaks.
B., They are caused by Pepsi machines exploding after being kicked by Coke drinkers.
C., Humanmade
atomicbomb
testing is responsible.
D., The deepest ones are caused by elastic rebound of bent rocks when a fault breaks, whereas shallower
ones are almost all caused by collapse of natural caves such as Mammoth Cave.
E., They are caused by Coke drinkers kicking the Pepsi machines in Penn State buildings.
“Implosion” is the currently favored idea. As subduction zones take rocks deeper where pressure is higher, the
building blocks tend to reorganize to take up less space, shifting from, say, a oneontopofanother
pattern to a
fitinthespacebetweenthosebelow
pattern. Sometimes, this seems to be delayed and then to happen all at
once (I can’t move until my neighbor does…), giving an implosion. The biggest, deepest earthquakes happen
where temperatures and pressures are so high that we don’t think rocks can break. Humans have never made
a hole anywhere nearly as deep as the deeper earthquakes. We have mostly quit testing atomic bombs. And, a
big earthquake is way bigger than a big atomic bomb. Penn State students, being naturally eventempered,
don’t kick hard enough to actually explode Pepsi machines. And Penn State basements are not deep enough to
account for the deeper earthquakes.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
13., Volcanic eruptions cause many hazards to humans, and many geologists are employed to study these
hazards and warn people. For a single, large, explosive volcanic eruption such as Mt. St. Helens, which of the
following is not a worry that these volcanichazards
geologists would warn people about?
, A., Pyroclastics, including bussized
pieces that could fall on people’s heads and kill them.
B., Tsunamis, or giant waves, that could drown people, if the volcano is in the ocean or a very large lake and
the eruption moves a lot of water out of the way.
C., Mudflows and landslides that could bury people and buildings.
D., Climatic warming, with the volcano causing a sudden heat wave that would harm people living in big cities.
E., Poisonous gases, that could kill people who breathe them in.
This is one of those interesting cases where “slow” and “fast” are different. Volcanoes release carbon dioxide,
and carbon dioxide warms. But carbon dioxide stays up a long time, and no single volcanic eruption puts up
enough carbon dioxide to make a detectable difference to the concentration in the air and the temperature of
the Earth. However, a single big eruption can put enough material into the stratosphere to block enough
sunlight to cool the Earth by a degree or two for a year or two. So the climatic hazard from a single big volcanic
eruption is cooling, not warming. Explosive volcanoes are often large and steep, and may have huge glaciers.
As heat melts the ice, and as melted rock moving into the volcano bulges the sides, huge landslides and
mudflows happen. Tens of thousands of people have been killed in single mudflows. Well over 100,000 people
live on the deposit from one old mudflow from Mt. Rainier (and those who know about that Osceola Flow really
hope it doesn’t happen again!). A tsunami is a big wave, caused by an earthquake, landslide, meteorite impact,
or volcanic eruption that displaces sea water. Waves can be 100 feet high or more, and do incredible damage.
A big eruption underwater can push a lot of water out of the way, making a tsunami. Pyroclastic flows are major
volcanic hazards, and can kill lots of people quickly. Imagine a fewhundreddegree
mixture of pulverized rock,
glass and poison gas chasing you at a few hundred miles per hour! Volcanoes do put out poison gases, such
as hydrogen sulfide or carbon dioxide (a little is good; too much is deadly!). When rocks melt a little, fluidand
gasmaking
materials preferentially end up in the melt rather than in the remaining rock, so eruptions commonly
come with gases, and some of those gases are of types or in concentrations that are not good for nearby
humans.
, Points Earned:, 0/1
Correct Answer:, D
Your Response:, B
,
14., The pictures show famous volcanoes, that we discussed in the class materials. Which statement is most
accurate about these?
, A., Picture II shows a headofhotspot
flood basalt, and picture I shows a subductionzonetype
throwssmallpieces
cinder cone.
B., Picture II shows a pile that a giant marmot named George dug up, and picture I shows a pile made by his
good friend Herb.
C., Picture II shows a hotspottype
shield volcano, and picture I shows a subductionzonetype
stratovolcano.
D., Picture II shows a subductionzonetype
flood basalt, and picture I shows a hotspottype
stratovolcano.
E., Picture II shows a headofhotspot
flood basalt, and picture I shows a throwssmallpieces
cinder cone.
Picture I is the glorious stratovolcano Lassen Peak, in the Cascades of northern California, and picture II is the
shield volcano of Mauna Loa, on the island of Hawaii.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
15., The volcanoes of the island of Hawaii eventually will:
, A., Last forever while nothing happens to them except for development of a protective layer of condominiums.
B., Blow up as powerfully as the main 1980 eruption of Mt. St. Helens.
C., Blow up as powerfully as the main eruptions of Yellowstone, 1000 times bigger than Mt. St. Helens.
D., Rise above sea level as they cool and sink, and are eroded.
E., Drift off the hot spot and cease to erupt, while a new volcano grows to their southeast.
As they drift off the hot spot, the Hawaiian chain volcanoes lose their source of melt and quit erupting. But, a
new volcano grows. Indeed, the new one, Loihi Seamount, is already there and erupting underwater, building
toward the surface. As they cool and sink, and are eroded, the Hawaiian volcanoes disappear below sea level.
Hawaiian volcanoes are “friendly”, not having highly explosive eruptions. Yellowstone is an anomaly; the hot
spot is not making a huge amount of melt, and that melt is modified in coming through the continent, so
Yellowstone explodes despite being a hot spot. But most hotspot
volcanoes are not highly explosive. The
“protective” layer of condominiums is developing in parts of Hawaii, but lots will happen to the volcanoes in
addition—earthquakes and eruptions and drifting and more—and wait until next time when we learn about
sides falling off!
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
///, 13
Points Missed, 2
Percentage, 87%
1., Which of the following is commonly expected near a “textbook” subduction zone (that is,
near a subduction zone that is so perfect and free of confusing complications that you would use
it in a textbook to teach students)?
, A., Slide-past (or transform, with horizontal but not vertical movement) earthquakes and faults,
such as occur along the San Andreas Fault.
B., Andesitic stratovolcanoes, such as Mt. St. Helens.
C., Pull-apart earthquakes and faults, such as occur in Death Valley.
D., Basaltic mid-ocean-ridge-type volcanoes, such as are found at undersea spreading ridges.
E., Basaltic hot-spot-type volcanoes, such as at Hawaii Volcanoes.
Pull-apart earthquakes and faults often occur at pull-apart basaltic mid-ocean ridges, which are
not subduction zones. Slide-past also occurs on the planet, but not primarily at subduction zones,
which also are not hot spots. But subduction does lead to layered thick-lava-flow/blown-up-bits
stratovolcanoes of andesitic composition.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
2., Volcanoes occur above the downgoing slab of a subduction zone. Why?
, A., The sediments scraped off the downgoing plate make a pile, such as the Olympic, and this
pile channels the Earth’s magnetic field along the slab to cause melting.
B., The downgoing slab takes water and other things along, which lower the melting point down
there enough to make melt that feeds the volcanoes.
C., The downgoing slab weakens the mantle, allowing hot-spots to come up along the slab and
feed the Hawaiian-type basaltic volcanoes that are characteristic of subduction zones.
D., The downgoing slab rubbing along the overlying rocks makes a lot of heat, thus making the
overlying rocks the hottest rocks in the mantle, which melts them to feed the volcanoes.
E., The downgoing slab causes earthquakes that weaken the mantle, allowing convection cells to
come up along the slab and feed the mid-ocean-ridge-type basaltic volcanoes that are
characteristic of subduction zones.
Throw a little dry flour in a warm oven, and not much happens. Add some water, or better, some
water and some carbon dioxide from yeast, and things happen in a hurry. The subduction zone
takes water, and carbon dioxide in shells and other things, down to lower the melting point and
feed volcanoes. Friction does warm the down-going slabs, but slabs start off way colder than the
rocks into which they move, and remain colder for a while. Sliding your cold feet along the
sheets when you get into bed on a winter night may warm your toes a little by friction, but if you
happen to share the bed with a significant other, putting your tootsies on that persons bare belly
will tell you that frictional heating takes a while! The scraped-off pile of sediment traps a tiny bit
of heat, but not too much; the downgoing slab makes the nearby mantle colder than normal, not
warmer. And nature tends to separate regions where something is flowing one way from regions
where the flow is reversed; if the flows are too close together, one will drag the other along and
change its direction. Hot spots occasionally ride along on spreading ridges, because both involve
rising, but not on subduction zones.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
,
3., Look at the picture above, from the coast of Olympic National Park. What happened here?
, A., First Mt. Mazama and then Mt. St. Helens blasted rocks and ash and dust through the air,
which fell as layers, with coarse at the bottom, fine on top from the first eruption, then coarse
and fine again from the next eruption, and so on.
B., Earthquakes knocked loose undersea muds that raced down the slopes of the west coast into
the subduction zone, making rocks that were then scraped off the downgoing slab to make part of
Olympic National Park.
C., The pocket knife was flushed out of an airline toilet by an absent-minded geologist.
D., The pocket knife was confiscated by government agents when an absent-minded geologist
tried to board an airline, and the government agents heaved it onto this rock.
E., Glaciers coming down from the high peaks of Olympic National Park ground over the surface
of the rock, carving the grooves we see.
Olympic is the pile of scraped-off stuff, and some of it fell into the trench rather recently during
earthquakes. There really are volcanic layers, and they can be sorted by size, but soils tend to
form between the eruptions, and the different eruptions will make different-looking layers. There
is a little bit of grooving across the rock face, from waves hitting the rock and some layers being
softer than others, but this is a very non-glacial-looking deposit. Amazing numbers of pocket
knives and other items are confiscated at airports, often from absent-minded geologists, but the
government agents don’t litter with those confiscated items. Airline toilets flush into holding
tanks on the plane, not onto people or rocks below, and very rarely have pocket knives because
the knives are confiscated first.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
4., Subduction zones produce an amazing variety of geological features. These include:
, A., Deep trenches in the sea floor, which are old river valleys eroded by the vigorous streams
flowing down from the mountains.
B., Deep trenches in the sea floor, which are really fjords eroded by glaciers flowing down from
the mountains and away from the coast out to sea.
C., Deep trenches in the sea floor, formed by the weight of discarded Microsoft Windows CDs
and Starbucks coffee cups, heaved into the ocean from Seattle by angry consumers.
D., Deep trenches in the sea floor, formed by the bending of the downgoing plate, but filled with
basaltic lava flows from the hot spots that feed the subduction-zone volcanoes.
E., Deep trenches in the sea floor, formed by the bending of the downgoing plate, and sometimes
filled with sea water but sometimes filled with sediment eroded from nearby land.
The deepest spots in the ocean are formed when downgoing slabs are bent downward to make
deep trenches parallel to the shore. However, sometimes these trenches become sediment-filled.
Microsoft CDs are a relatively small part of that sediment. Rivers don’t cut below sea level, and
glaciers flowing away from the coast cannot cut a huge trench parallel to the coast.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
5., Rocks in continents are on average much older than sea-floor rocks. The likely explanation is:
, A., Old sea floor is recycled back into the deep mantle at subduction zones at the same rate that
new sea floor is produced, but continents are not taken into the mantle and so remain on the
surface for a long time.
B., For a long time the Earth had continents but no sea floor; only recently, Death-Valley-type
spreading has split continents to make sea floor.
C., Techniques used to estimate the age of the rocks all yield perfect ages for continental rocks
but wild errors for sea-floor rocks, and sea-floor rocks are really as old as the continents.
D., For a long time the Earth had continents but no sea floor; only recently, continents sank and
allowed lakes to grow into oceans.
E., So much undersea mining has been conducted to get valuable metals from old sea-floor rocks
that all of the old ones have been ground up by people.
Subduction balances sea-floor production very very closely, so the planet retains the same size
and density distribution over time. Continents have grown slowly, but once made, the lowdensity
continental rocks stay on the surface, whereas sea-floor rocks are lost to the deep mantle
at subduction zones. Geological evidence indicates that we have had ocean basins since just after
the formation of the planet. And undersea mining so far has been very tiny and localized.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
6., You see a hot-spot volcano on the surface of the Earth. What is under this volcano?
, A., A spreading ridge, where sea floor is made.
B., A subduction zone, where volcanic arcs are made.
C., A subduction zone, which brings up rock from deep in the mantle.
D., A rising tower of hot rock from deeper in the mantle, and perhaps all the way from the
bottom of the mantle.
E., A Pepsi machine.
Earthquakes make sound waves that go through the whole Earth, and go slower through hotter,
less-dense rocks. By setting out listening devices called seismometers around the Earth, and
listening to the waves from many earthquakes in many places, scientists can map the hotter
regions, and find that towers of hot rock come up from way deep in the Earth in some places.
But, some other hot spots, while clearly coming up from below, don’t seem to start quite as deep.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
7., Most commonly, a hot-spot volcano:
, A., Is mostly andesitic in composition, with gradual sides where the volcano projects above sea
level, but steeper sides on undersea portions.
B., Is basaltic in composition, with gradual sides where the volcano projects above sea level, but
steeper sides on undersea portions.
C., Is andesitic in composition, and shaped like a Pepsi can, with vertical sides below sea level.
D., Is lower in silica than basalt, more like the mantle from which the hot-spot lava comes, with
gradual sides where the volcano projects above sea level, but steeper sides on undersea portions.
E., Is mostly andesitic in composition, with steep sides where the volcano projects above sea
level, but less-steep sides on undersea portions.
The rising hot rock of hot spots feeds volcanoes. Both sea floor and hot-spot volcanoes come
from melting a little of the very-low-silica mantle, pulling out the melt, and freezing it, and so
are basaltic (low-silica) volcanoes. Note, though, that a few hotspots (such as Yellowstone) are
not basaltic, because the basalt has been altered in getting through the continent. The melt
probably started out as something that would make basalt, and indeed, the Yellowstone hot-spot
track includes basaltic lavas such as those at the glorious Craters of the Moon National
Monument. The hot-spot lavas are runny, and spread easily under the air to make volcanoes with
gradual slopes, unlike the steep stratovolcanoes, although the slopes of hot-spot volcanoes are
steeper under water because the water cools the lava so rapidly that it can’t spread far.
, Points Earned:, 0/1
Correct Answer:, B
Your Response:, D
,
8., Look at the picture above. What happened here?
, A., A sharp bend in a river created a whirlpool that carved the hole now filled by a lake.
B., A giant glacier used to sit here, and water flowing into a hole on the surface fell to the bed
and hollowed out a great pothole, seen here.
C., A great volcanic explosion occurred, spreading material across the landscape and leaving a
hole.
D., Death-Valley-type faulting dropped the bottom, making space for the lake; during the Ice
Age, Death Valley looked like this, too.
E., An immense marmot named George, shown here, dug the hole.
Nature has many ways to make holes, and many other ways to make mountains. Part of this class
is learning to read the clues, just as geologists do. We saw at Death Valley that the faults tend to
make straight lines. Streams on glaciers are not nearly this big, nor are river bends. And while
George is cute, he could never dig such a hole. This is the aftermath of the eruption of Mt. St.
Helens.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
9., Major differences between Mt. St. Helens and Hawaiian volcanoes include:
, A., Mt. St. Helens is a medium-to-high-silica, quietly erupting shield volcano, and Hawaii has
low-silica, explosively erupting stratovolcanoes.
B., Mt. St. Helens is a low-silica, explosively erupting stratovolcano, and Hawaii has medium-tohigh-
silica, quietly erupting shield volcanoes.
C., Mt. St. Helens is a volcano, but Hawaii doesn’t have any volcanoes, and never has.
D., Mt. St. Helens is a low-silica, quietly erupting shield volcano, and Hawaii has medium-tohigh-
silica, explosively erupting stratovolcanoes.
E., Mt. St. Helens is a medium-to-high-silica, explosively erupting stratovolcano, and Hawaii has
low-silica, quietly erupting shield volcanoes.
The low-silica lava from the Hawaiian hot spot flows easily without large explosions, so the lava
spreads out to make broad, gentle volcanoes that look like shields of medieval warriors. Melt a
little basaltic sea floor with some water and sediment, and you get silica-rich andesite feeding
explosive, subduction-zone stratovolcanoes such as Mt. St. Helens. Hot spots and spreading
ridges make low-silica, basaltic volcanoes, which don’t explode powerfully. Mt. St. Helens is a
stratovolcano, but stratovolcanoes are steep, not broad and flat. Mt. St. Helens was the most
active of the Cascades volcanoes even before its big 1980 eruption, and the volcano has erupted
many times since the big eruption.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
10., You get in your Magic School Bus, drive down the throat of a volcano, and find that you are
driving through melted rock that does not make lumps but flows more easily than does most
melted rock. It is likely that the melted rock you are driving through:
, A., Is especially low in water and carbon dioxide compared to most melted rocks.
B., Is being stirred rapidly by Teletubbies.
C., Is especially rich in water and carbon dioxide compared to most melted rocks.
D., Is especially poor in iron and other things that would get between silicon-oxygen tetrahedra,
compared to most melted rocks.
E., Is especially cool compared to most melted rocks.
The silicon-oxygen tetrahedra link up to make lumps, so anything that gets in the way of this
linking will oppose lumping. Iron, water, carbon dioxide, or high heat that shakes the lumps apart
can all oppose the lumping of polymerization.
, Points Earned:, 0/1
Correct Answer:, C
Your Response:, A
,
11., Look at the picture above. Here is new land forming in Hawaii, where lava enters the sea.
What is happening here?
, A., Earthquakes are occurring, tearing the rocks open to let the lava out.
B., Lava is erupting from beneath the sea and squirting onto the black rock.
C., The Pacific Ring of Fire is forming in front of your eyes, as subduction produces volcanic
eruptions of red-hot lava.
D., The lava flow has cooled on the sides and is draining out the middle. Eventually, if more lava
is not supplied at the other end of the tubes to replace the lava that is draining out, the lava tubes
may empty and leave caves.
E., A giant marmot, named George, is taking a leak.
Lava comes out of the volcano hot (roughly 2000 degrees F), but chills quickly where in contact
with the air or with older, colder rocks. This typically makes the tops, sides, and bottoms of a
flow colder than the middle. If the middle finds a way to flow out, a tube can be left behind.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
12., Earthquakes can be caused in many different ways. The best interpretation of the planet’s
earthquakes is that:
, A., The rare, deepest ones are caused by “implosion” as minerals in downgoing slabs of
subduction zones suddenly switch to a denser arrangement, whereas common shallower ones are
caused by elastic rebound of bent rocks when a fault breaks.
B., The deepest ones are caused by elastic rebound of bent rocks when a fault breaks, whereas
shallower ones are almost all caused by collapse of natural caves such as Mammoth Cave.
C., They are caused by Pepsi machines exploding after being kicked by Coke drinkers.
D., Human-made atomic-bomb testing is responsible.
E., They are caused by Coke drinkers kicking the Pepsi machines in Penn State buildings.
“Implosion” is the currently favored idea. As subduction zones take rocks deeper where pressure
is higher, the building blocks tend to reorganize to take up less space, shifting from, say, a oneon-
top-of-another pattern to a fit-in-the-space-between-those-below pattern. Sometimes, this
seems to be delayed and then to happen all at once (I can’t move until my neighbor does…),
giving an implosion. The biggest, deepest earthquakes happen where temperatures and pressures
are so high that we don’t think rocks can break. Humans have never made a hole anywhere
nearly as deep as the deeper earthquakes. We have mostly quit testing atomic bombs. And, a big
earthquake is way bigger than a big atomic bomb. Penn State students, being naturally eventempered,
don’t kick hard enough to actually explode Pepsi machines. And Penn State basements
are not deep enough to account for the deeper earthquakes.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
13., Volcanic eruptions cause many hazards to humans, and many geologists are employed to
study these hazards and warn people. For a single, large, explosive volcanic eruption such as Mt.
St. Helens, which of the following is not a worry that these volcanic-hazards geologists would
warn people about?
, A., Tsunamis, or giant waves, that could drown people, if the volcano is in the ocean or a very
large lake and the eruption moves a lot of water out of the way.
B., Pyroclastics, including bus-sized pieces that could fall on people’s heads and kill them.
C., Poisonous gases, that could kill people who breathe them in.
D., Mudflows and landslides that could bury people and buildings.
E., Climatic warming, with the volcano causing a sudden heat wave that would harm people
living in big cities.
This is one of those interesting cases where “slow” and “fast” are different. Volcanoes release
carbon dioxide, and carbon dioxide warms. But carbon dioxide stays up a long time, and no
single volcanic eruption puts up enough carbon dioxide to make a detectable difference to the
concentration in the air and the temperature of the Earth. However, a single big eruption can put
enough material into the stratosphere to block enough sunlight to cool the Earth by a degree or
two for a year or two. So the climatic hazard from a single big volcanic eruption is cooling, not
warming. Explosive volcanoes are often large and steep, and may have huge glaciers. As heat
melts the ice, and as melted rock moving into the volcano bulges the sides, huge landslides and
mudflows happen. Tens of thousands of people have been killed in single mudflows. Well over
100,000 people live on the deposit from one old mudflow from Mt. Rainier (and those who know
about that Osceola Flow really hope it doesn’t happen again!). A tsunami is a big wave, caused
by an earthquake, landslide, meteorite impact, or volcanic eruption that displaces sea water.
Waves can be 100 feet high or more, and do incredible damage. A big eruption underwater can
push a lot of water out of the way, making a tsunami. Pyroclastic flows are major volcanic
hazards, and can kill lots of people quickly. Imagine a few-hundred-degree mixture of pulverized
rock, glass and poison gas chasing you at a few hundred miles per hour! Volcanoes do put out
poison gases, such as hydrogen sulfide or carbon dioxide (a little is good; too much is deadly!).
When rocks melt a little, fluid- and gas-making materials preferentially end up in the melt rather
than in the remaining rock, so eruptions commonly come with gases, and some of those gases are
of types or in concentrations that are not good for nearby humans.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
,
14., The pictures show famous volcanoes, that we discussed in the class materials. Which
statement is most accurate about these?
, A., Picture II shows a head-of-hot-spot flood basalt, and picture I shows a subduction-zone-type
throws-small-pieces cinder cone.
B., Picture II shows a subduction-zone-type flood basalt, and picture I shows a hot-spot-type
stratovolcano.
C., Picture II shows a head-of-hot-spot flood basalt, and picture I shows a throws-small-pieces
cinder cone.
D., Picture II shows a pile that a giant marmot named George dug up, and picture I shows a pile
made by his good friend Herb.
E., Picture II shows a hot-spot-type shield volcano, and picture I shows a subduction-zone-type
stratovolcano.
Picture I is the glorious stratovolcano Lassen Peak, in the Cascades of northern California, and
picture II is the shield volcano of Mauna Loa, on the island of Hawaii.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
15., What is the “Ring of Fire”?
, A., The melted outer core ringing the solid inner core of the planet.
B., The circle of basaltic volcanoes around Death Valley.
C., The complex of volcanic arcs fed by subduction zones encircling the Pacific Ocean.
D., The circle of lava flows seen at night around a Hawaiian shield volcano.
E., The ring of Coke drinkers around a Pepsi machine.
The “Ring of Fire” is the circle of volcanic arcs fed by subduction zones with scraped-off muds
and deep earthquakes around the Pacific Ocean.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
///, 14
Points Missed, 1
Percentage, 93%
1., Which of the following is commonly expected near a “textbook” subduction zone (that is,
near a subduction zone that is so perfect and free of confusing complications that you would use
it in a textbook to teach students)?
, A., Basaltic mid-ocean-ridge-type volcanoes, such as are found at undersea spreading ridges.
B., Slide-past (or transform, with horizontal but not vertical movement) earthquakes and faults,
such as occur along the San Andreas Fault.
C., Andesitic stratovolcanoes, such as Mt. St. Helens.
D., Basaltic hot-spot-type volcanoes, such as at Hawaii Volcanoes.
E., Pull-apart earthquakes and faults, such as occur in Death Valley.
Pull-apart earthquakes and faults often occur at pull-apart basaltic mid-ocean ridges, which are
not subduction zones. Slide-past also occurs on the planet, but not primarily at subduction zones,
which also are not hot spots. But subduction does lead to layered thick-lava-flow/blown-up-bits
stratovolcanoes of andesitic composition.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
2., Melting happens in association with a subduction zone. What is going on to cause this?
, A., The motion of the downgoing slab weakens the mantle so that a hot spot from deep below
can rise along the downgoing slab and cause melting.
B., The scraped-off pile from the subduction zone traps the Earth’s heat beneath, and the
downgoing slab passes through this hot zone and melts in response.
C., The downgoing slab takes along water, and that water lowers the temperature at which rock
melts to allow melting in and near the slab.
D., The bending and friction associated with scraping off a pile of sediment, such as the Olympic
Peninsula, makes the pile very hot, and the downgoing slab passes through the hot zone and
melts in response.
E., The immense friction between the downgoing slab and the overlying rocks makes the slab the
hottest things in the mantle, causing much melting nearby.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
,
3., The picture shows some rocks on the beach at Olympic National Park. The pocket knife is
about 3 inches (or 8 cm) long. What is the story of these rocks?
, A., Earthquakes knocked loose undersea muds that raced down the slope into the subduction
zone to make these layered rocks, which were scraped off the downgoing slab, part of the
process by which continents grow as material is added to their edges at subduction zones.
B., The layering comes from different volcanic eruptions that piled material on the beach, as part
of the process by which spreading zones tear apart continents, causing them to become smaller
over time.
C., The pocket knife was flushed out of an airline toilet by an absent-minded geologist, and fell
on the rock.
D., The pocket knife washed overboard from a Chinese freighter in a storm, and floated to the
beach on the currents; scientists use the distribution of such flotsam and jetsam to learn about the
oceanic currents that drive plate tectonics.
E., Earthquakes knocked loose undersea muds that raced down the slope into the subduction
zone to make these layered rocks, which were scraped off the downgoing slab, part of the
process by which continents shrink as material is scraped off their edges at subduction zones.
Olympic is the pile of scraped-off stuff, and some of it fell into the trench rather recently during
earthquakes. Build-up of material above subduction zones contributes to growth of continents
over time, not shrinkage. There really are volcanic layers, but as described in the slide show,
these are not volcanic layers, and continents grow over time rather than shrinking. Things do
wash off freighters, and items such as rubber ducks and shoes have been used to trace ocean
currents, but pocket knives sink, and ocean currents are not the driving force for drifting plates.
Airline toilets flush into holding tanks on the plane, not onto people or rocks below, and very
rarely have pocket knives because the knives are confiscated first.
, Points Earned:, 0/1
Correct Answer:, A
Your Response:, E
4., Subduction zones produce an amazing variety of geological features. These include:
, A., Deep trenches in the sea floor, which are old river valleys eroded by the vigorous streams
flowing down from the mountains.
B., Deep trenches in the sea floor, formed by the bending of the downgoing plate, but filled with
basaltic lava flows from the hot spots that feed the subduction-zone volcanoes.
C., Deep trenches in the sea floor, which are really fjords eroded by glaciers flowing down from
the mountains and away from the coast out to sea.
D., Deep trenches in the sea floor, formed by the bending of the downgoing plate, and sometimes
filled with sea water but sometimes filled with sediment eroded from nearby land.
E., Deep trenches in the sea floor, formed by the weight of discarded Microsoft Windows CDs
and Starbucks coffee cups, heaved into the ocean from Seattle by angry consumers.
The deepest spots in the ocean are formed when downgoing slabs are bent downward to make
deep trenches parallel to the shore. However, sometimes these trenches become sediment-filled.
Microsoft CDs are a relatively small part of that sediment. Rivers don’t cut below sea level, and
glaciers flowing away from the coast cannot cut a huge trench parallel to the coast.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
5., You use highly accurate techniques to learn the time when lots and lots of different volcanic
rocks solidified from melted rock. You do this for many different rocks across the continents, and
many different rocks across the sea floor. You will find that (note that “older” rocks are those that
solidified more years ago, and “younger” rocks are those that solidified fewer years ago.):
, A., The sea-floor rocks are typically older than the continental rocks, because the sea-floor
rocks formed first and then the continental rocks fell on top of them as the planet grew.
B., The sea-floor rocks and the continental rocks are typically of about the same age.
C., The sea-floor rocks are typically younger than the continental rocks, because some of the
older continental rocks were blasted away by the collision that made the moon, revealing the
younger sea-floor rocks beneath.
D., The sea-floor rocks are typically younger than the continental rocks, because sea-floor rocks
are taken back into the mantle at subduction zones about as rapidly as new sea-floor rocks are
produced, while continental rocks are not taken back into the mantle at subduction zones.
E., The sea-floor rocks are typically older than the continental rocks, because the sea-floor rocks
formed first and then they were melted to make the continental rocks.
You can find young rocks on the sea floor and on the continents, but all of the old rocks on the
planet are on continents—there are no old sea-floor rocks. The older sea floor has all been
recycled at subduction zones.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
6., Volcanoes of many different types can be observed at the surface of the Earth. Suppose you
are looking at a hot-spot volcano. If you could see deep beneath that volcano, what would you
find?
, A., A Pepsi machine, that has been shaken by earthquakes so that the bottles are exploding.
B., A volcanic-arc-producing, Ring-of-Fire type subduction zone.
C., A sea-floor-producing spreading ridge.
D., A scraped-off pile of material, heated by the off-scraping and melting in the middle to feed
the volcano.
E., A rising tower of hot rock, coming up from below and perhaps from waaaaay below, down at
the bottom of the mantle.
Earthquakes make sound waves that go through the whole Earth, and go slower through hotter,
less-dense rocks. By setting out listening devices called seismometers around the Earth, and
listening to the waves from many earthquakes in many places, scientists can map the hotter
regions, and find that towers of hot rock come up from way deep in the Earth in some places.
But, some other hot spots, while clearly coming up from below, don’t seem to start quite as deep.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
7., What is accurate about a typical volcano formed by eruptions from a hot spot?
, A., The lava of the volcano is mostly andesitic in composition, with gradual sides where the
volcano projects above sea level, but steeper sides on undersea portions.
B., The lava of the volcano is andesitic in composition, and the volcano itself is shaped like a
Pepsi can, with vertical sides below sea level.
C., The lava of the volcano is mostly andesitic in composition, and the volcano itself has steep
sides where projecting above sea level, but less-steep sides on undersea portions.
D., The lava of the volcano contains less silica than basalt has, and thus is like the mantle in
composition because the melt comes from the mantle, and the volcano itself has uniformly
sloping sides like the beautiful peak of Mt. St. Helens before the 1980 eruption.
E., The lava of the volcano is mostly basaltic in composition, with gradual sides where the
volcano projects above sea level, but steeper sides on undersea portions.
The rising hot rock of hot spots feeds volcanoes. Both sea floor and hot-spot volcanoes come
from melting a little of the very-low-silica mantle, pulling out the melt, and freezing it, and so
are basaltic (low-silica) volcanoes. Note, though, that a few hotspots (such as Yellowstone) are
not basaltic, because the basalt has been altered in getting through the continent. The melt
probably started out as something that would make basalt, and indeed, the Yellowstone hot-spot
track includes basaltic lavas such as those at the glorious Craters of the Moon National
Monument. The hot-spot lavas are runny, and spread easily under the air to make volcanoes with
gradual slopes, unlike the steep stratovolcanoes, although the slopes of hot-spot volcanoes are
steeper under water because the water cools the lava so rapidly that it can’t spread far.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
,
8., Look at the picture above. What happened here?
, A., A giant glacier used to sit here, and water flowing into a hole on the surface fell to the bed
and hollowed out a great pothole, seen here.
B., An immense marmot named George, shown here, dug the hole.
C., A sharp bend in a river created a whirlpool that carved the hole now filled by a lake.
D., A great volcanic explosion occurred, spreading material across the landscape and leaving a
hole.
E., Death-Valley-type faulting dropped the bottom, making space for the lake; during the Ice
Age, Death Valley looked like this, too.
Nature has many ways to make holes, and many other ways to make mountains. Part of this class
is learning to read the clues, just as geologists do. We saw at Death Valley that the faults tend to
make straight lines. Streams on glaciers are not nearly this big, nor are river bends. And while
George is cute, he could never dig such a hole. This is the aftermath of the eruption of Mt. St.
Helens.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
9., Major differences between Mt. St. Helens and Hawaiian volcanoes include:
, A., Mt. St. Helens is a low-silica, explosively erupting stratovolcano, and Hawaii has mediumto-
high-silica, quietly erupting shield volcanoes.
B., Mt. St. Helens is a medium-to-high-silica, quietly erupting shield volcano, and Hawaii has
low-silica, explosively erupting stratovolcanoes.
C., Mt. St. Helens is a medium-to-high-silica, explosively erupting stratovolcano, and Hawaii has
low-silica, quietly erupting shield volcanoes.
D., Mt. St. Helens is a volcano, but Hawaii doesn’t have any volcanoes, and never has.
E., Mt. St. Helens is a low-silica, quietly erupting shield volcano, and Hawaii has medium-tohigh-
silica, explosively erupting stratovolcanoes.
The low-silica lava from the Hawaiian hot spot flows easily without large explosions, so the lava
spreads out to make broad, gentle volcanoes that look like shields of medieval warriors. Melt a
little basaltic sea floor with some water and sediment, and you get silica-rich andesite feeding
explosive, subduction-zone stratovolcanoes such as Mt. St. Helens. Hot spots and spreading
ridges make low-silica, basaltic volcanoes, which don’t explode powerfully. Mt. St. Helens is a
stratovolcano, but stratovolcanoes are steep, not broad and flat. Mt. St. Helens was the most
active of the Cascades volcanoes even before its big 1980 eruption, and the volcano has erupted
many times since the big eruption.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
10., You get in your Magic School Bus, drive down the throat of a volcano, and find that you are
driving through melted rock that flows with much greater difficulty than does most melted rock,
because the melted rock you are driving through is lumpier than typical for melted rock. It is
likely that the melted rock you are driving through is:
, A., Especially rich in Diet Pepsi compared to most melted rocks.
B., Especially warm compared to most melted rocks.
C., Especially rich in water and carbon dioxide compared to most melted rocks.
D., Especially rich in iron and other things that would get between silicon-oxygen tetrahedra,
compared to most melted rocks.
E., Especially low in water and carbon dioxide compared to most melted rocks.
The silicon-oxygen tetrahedra link up to make lumps, so anything that gets in the way of this
linking will oppose lumping. Iron, water, carbon dioxide, or high heat that shakes the lumps apart
can all oppose the lumping of polymerization. Diet Pepsi would break up lumps, too, although
isn’t especially likely in melted rock.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
,
11., These two pictures are from Hawaii Volcanoes National Park, on the flanks of Kilauea
Volcano. How are pictures I and II related?
, A., Subduction processes open tubes such as shown in I, and then later when volcanic eruptions
happen, the lava uses those tubes as shortcuts to the sea, as shown in II.
B., Lava flows chill on top and sides while the unchilled central part continues flowing as shown
in II, and if more lava is not supplied to keep the tubes filled, the tubes may drain to leave caves,
such as the one shown in I.
C., Lava flows chill on top and sides while the unchilled central part continues flowing as shown
in II, and later after the central part chills too, it is dissolved more easily by acidic groundwaters
because it froze later, leaving caves such as the one shown in I.
D., Lava flows chill on top and sides while the unchilled central part continues flowing as shown
in II, and later after the central part chills too, it is mined out by the Park Service because it is
softer, making visitor-entertaining caves, such as the one shown in I.
E., Earthquakes open tubes such as shown in I, and then later when volcanic eruptions happen,
the lava uses those tubes as shortcuts to the sea, as shown in II.
2000-degree lava hits 70-degree air on top and sides, and 70-degree rock on the bottom, when
the lava first flows out of the volcano, so the lava tends to freeze on all sides. Often, though, the
lava will flow downhill away from the volcano fast enough that the leading edge will break as
rapidly as it chills, and thus the end won’t get plugged, allowing the sort of lava flow seen in II.
Stop the supply of melted rock to the volcano end of the tube, the tube drains out, and a cave is
left, such as the beautiful one seen in II.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
12., Earthquakes can be caused in many different ways. The best interpretation of the planet’s
earthquakes is that:
, A., The deepest ones are caused by elastic rebound of bent rocks when a fault breaks, whereas
shallower ones are almost all caused by collapse of natural caves such as Mammoth Cave.
B., They are caused by Coke drinkers kicking the Pepsi machines in Penn State buildings.
C., The rare, deepest ones are caused by “implosion” as minerals in downgoing slabs of
subduction zones suddenly switch to a denser arrangement, whereas common shallower ones are
caused by elastic rebound of bent rocks when a fault breaks.
D., Human-made atomic-bomb testing is responsible.
E., They are caused by Pepsi machines exploding after being kicked by Coke drinkers.
“Implosion” is the currently favored idea. As subduction zones take rocks deeper where pressure
is higher, the building blocks tend to reorganize to take up less space, shifting from, say, a oneon-
top-of-another pattern to a fit-in-the-space-between-those-below pattern. Sometimes, this
seems to be delayed and then to happen all at once (I can’t move until my neighbor does…),
giving an implosion. The biggest, deepest earthquakes happen where temperatures and pressures
are so high that we don’t think rocks can break. Humans have never made a hole anywhere
nearly as deep as the deeper earthquakes. We have mostly quit testing atomic bombs. And, a big
earthquake is way bigger than a big atomic bomb. Penn State students, being naturally eventempered,
don’t kick hard enough to actually explode Pepsi machines. And Penn State basements
are not deep enough to account for the deeper earthquakes.
, Points Earned:, 1/1
Correct Answer:, C
Your Response:, C
13., Volcanic eruptions cause many hazards to humans, and many geologists are employed to
study these hazards and warn people. For a single, large, explosive volcanic eruption such as Mt.
St. Helens, which of the following is not a worry that these volcanic-hazards geologists would
warn people about?
, A., Poisonous gases, that could kill people who breathe them in.
B., Tsunamis, or giant waves, that could drown people, if the volcano is in the ocean or a very
large lake and the eruption moves a lot of water out of the way.
C., Mudflows and landslides that could bury people and buildings.
D., Climatic warming, with the volcano causing a sudden heat wave that would harm people
living in big cities.
E., Pyroclastics, including bus-sized pieces that could fall on people’s heads and kill them.
This is one of those interesting cases where “slow” and “fast” are different. Volcanoes release
carbon dioxide, and carbon dioxide warms. But carbon dioxide stays up a long time, and no
single volcanic eruption puts up enough carbon dioxide to make a detectable difference to the
concentration in the air and the temperature of the Earth. However, a single big eruption can put
enough material into the stratosphere to block enough sunlight to cool the Earth by a degree or
two for a year or two. So the climatic hazard from a single big volcanic eruption is cooling, not
warming. Explosive volcanoes are often large and steep, and may have huge glaciers. As heat
melts the ice, and as melted rock moving into the volcano bulges the sides, huge landslides and
mudflows happen. Tens of thousands of people have been killed in single mudflows. Well over
100,000 people live on the deposit from one old mudflow from Mt. Rainier (and those who know
about that Osceola Flow really hope it doesn’t happen again!). A tsunami is a big wave, caused
by an earthquake, landslide, meteorite impact, or volcanic eruption that displaces sea water.
Waves can be 100 feet high or more, and do incredible damage. A big eruption underwater can
push a lot of water out of the way, making a tsunami. Pyroclastic flows are major volcanic
hazards, and can kill lots of people quickly. Imagine a few-hundred-degree mixture of pulverized
rock, glass and poison gas chasing you at a few hundred miles per hour! Volcanoes do put out
poison gases, such as hydrogen sulfide or carbon dioxide (a little is good; too much is deadly!).
When rocks melt a little, fluid- and gas-making materials preferentially end up in the melt rather
than in the remaining rock, so eruptions commonly come with gases, and some of those gases are
of types or in concentrations that are not good for nearby humans.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
,
14., The pictures show famous volcanoes, that we discussed in the class materials. Which
statement is most accurate about these?
, A., Picture II shows a subduction-zone-type flood basalt, and picture I shows a hot-spot-type
stratovolcano.
B., Picture II shows a head-of-hot-spot flood basalt, and picture I shows a subduction-zone-type
throws-small-pieces cinder cone.
C., Picture II shows a head-of-hot-spot flood basalt, and picture I shows a throws-small-pieces
cinder cone.
D., Picture II shows a hot-spot-type shield volcano, and picture I shows a subduction-zone-type
stratovolcano.
E., Picture II shows a pile that a giant marmot named George dug up, and picture I shows a pile
made by his good friend Herb.
Picture I is the glorious stratovolcano Lassen Peak, in the Cascades of northern California, and
picture II is the shield volcano of Mauna Loa, on the island of Hawaii.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
15., What is the “Ring of Fire”?
, A., The circle of basaltic volcanoes around Death Valley.
B., The circle of lava flows seen at night around a Hawaiian shield volcano.
C., The melted outer core ringing the solid inner core of the planet.
D., The ring of Coke drinkers around a Pepsi machine.
E., The complex of volcanic arcs fed by subduction zones encircling the Pacific Ocean.
The “Ring of Fire” is the circle of volcanic arcs fed by subduction zones with scraped-off muds
and deep earthquakes around the Pacific Ocean.
, Points Earned:, 1/1
Correct Answer:, E
Your Response:, E
///, 14
Points Missed, 1
Percentage, 93%
1., Which of the following is not expected very often near a “textbook” subduction zone (that is, near a
subduction zone that is so perfect and free of confusing complications that you would use it in a textbook to
teach students)?
, A., Piles of sediment scraped off the downgoing slab.
B., Explosive volcanoes.
C., Slidepast
(or transform, with horizontal but no vertical movement) earthquakes and faults.
D., Pushtogether
earthquakes and faults.
E., Stratovolcanoes.
Most of the action at subduction zones is “pushtogether”,
including pushtogether
earthquakes and faults,
scraping off of sediment to make piles as one side moves under the other side, and volcanic explosions that
contribute to layered volcanoes, or “stratovolcanoes”. Slidepast
motion is not dominant, intermediates between
pure subduction and pure slidepast
motion do exist, but are not “textbook” cases of subduction.
, Points Earned:, 0/1
Correct Answer:, C
Your Response:, E
2., Much melting in the mantle occurs near subducting slabs primarily because:
, A., Water taken down subduction zones lowers the melting temperature in and near the slabs.
B., Sediments scraped off downgoing slabs pile up, trapping heat and causing the rocks below to be warmer
than elsewhere in the mantle.
C., Convection cells from the deep mantle rise along subduction zones.
D., Slabs are the hottest things in the mantle because of friction from the subduction.
E., Hot spots come up subduction zones.
Throw a little dry flour in a warm oven, and not much happens. Add some water, or better, some water and
some carbon dioxide from yeast, and things happen in a hurry. The subduction zone takes water, and carbon
dioxide in shells and other things, down to lower the melting point and feed volcanoes. Friction does warm the
downgoing
slabs, but slabs start off way colder than the rocks into which they move, and remain colder for a
while. Sliding your cold feet along the sheets when you get into bed on a winter night may warm your toes a
little by friction, but if you happen to share the bed with a significant other, putting your tootsies on that persons
bare belly will tell you that frictional heating takes a while! The scrapedoff
pile of sediment traps a tiny bit of
heat, but not too much; the downgoing slab makes the nearby mantle colder than normal, not warmer. And
nature tends to separate regions where something is flowing one way from regions where the flow is reversed;
if the flows are too close together, one will drag the other along and change its direction. Hot spots occasionally
ride along on spreading ridges, because both involve rising, but not on subduction zones.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
3., Continents:
, A., Have grown in area over time primarily by hot spots erupting through continents to produce suspect
terranes.
B., Have grown in area over time primarily by addition of island arcs, seamounts and sediments scraped off
subducting slabs.
C., Have not changed their areas over time.
D., Have grown in area over time primarily because convection cells stretched and thinned continents but never
pulled them apart to make new ocean basins.
E., Once covered the entire surface of the Earth, but have shrunk over time as convection cells pulled them
apart to make ocean basins.
Observations show that the continents have grown, as pieces were added to the continent sides; the centers of
continents are very old, and then younger rocks occur in belts around the old cores. If you kept loading the
conveyorbelt
at the grocery store, but there were no baggers and you refused to bag your own, you’d end up
with a giant clot of groceries mashed together at the end. That is not a bad model for how continents form. If a
watermelon runs into a loaf of bread, you get a big mountainbuilding
event! Hot spots poke through continents
occasionally, but don’t cause much spreading so don’t cause much continental growth. “Suspect terrane” is an
old geologic term for rocks that drifted in on a subducting slab and then mashed up onto a continent.
Geologists long “suspect”ed that these “terranes” were weird, and eventually figured out the explanation, but
named them before learning the explanation. Continents can be stretched and thinned at spreading centers,
and some of those spreading centers do fail and leave a stretched continent that hasn’t broken to make an
ocean, but more commonly the stretching continues until an ocean is made.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
4., There is a deep trench in the sea floor off the Marianas volcanic arc of explosive, andesitic, Ring of Fire
volcanoes in the South Pacific, but the water is not deep off the coast of Oregon and Washington near Mt. St.
Helens and the Olympic, because:
, A., Oregon and Washington are near a subduction zone, but the Marianas are not.
B., The Marianas, Oregon and Washington have trenches, but the trench off Oregon and Washington is filled
by discarded Microsoft Windows CDs that are obsolete because of all the virus problems.
C., The trench off Oregon and Washington is filled with great basaltic lava flows from the hot spot that feeds the
Cascades volcanoes.
D., The Marianas, Oregon and Washington have had the sea floor bent downward by subduction to make
trenches, the trench off Oregon and Washington is filled by sediment eroded from the nearby continent, but the
Marianas don’t have a nearby continent and so the trench there is not filled with sediment.
E., The Marianas are near a subduction zone, but Oregon and Washington are not.
The more rocks there are nearby, the easier it is for erosion to move some of those rocks. The trench off
Oregon and Washington has Oregon and Washington nearby, with lots of rocks. Add in that Oregon and
Washington have great rivers such as the Columbia, and huge glaciers that grind up the rocks such as the
beautiful glaciers on Mt. Rainier, and there is lots of sediment to fill the trench and be scraped off the
subduction zone to make Olympic National Park. The Marianas involve subduction of older, colder sea floor
under younger, warmer sea floor, have less rock above sea level nearby to be eroded, are in a warm place
without glaciers, and so haven’t filled the nearby trench with sediment. There probably are a few discarded
floppy disks, as well as a lot of other humanproduced
material, in the trench off Oregon and Washington, but
nature has been a lot more important than humans in filling the trenches. Humans did once talk about
disposing of radioactive waste in the trenches, but then we found out that whatever goes down the trench
comes back up, and may be squeezed and broken and squirted back up quickly, so we gave up on that idea.
And the volcanoes of Oregon and Washington are subductionzone
volcanoes, not hotspot
volcanoes.
, Points Earned:, 1/1
Correct Answer:, D
Your Response:, D
5., The sea floor that forms at spreading ridges and then moves away will:
, A., Be subducted, with most of the material going back into the mantle, balancing the material coming out to
make the new sea floor.
B., Remain at the surface of the earth forever, but the earth isn’t getting bigger because the insides of the earth
are shrinking as they cool off rapidly.
C., Be ground up by glaciers, blown away by wind, and eventually escape to space in the solar wind.
D., Remain at the surface of the earth forever, resulting in the earth getting bigger and bigger every year.
E., Be bulldozed and used as construction material for the new building on campus.
Seafloor rocks are generally not very old (perhaps 160 million years old at the most). By contrast, continental
rocks are up to 4 billion years old. The reason is that seafloor rocks are created (at midocean spreading ridges)
and then consumed (at subduction zones) continuously, and at about the same rate. Oceanic rocks are denser
than continental rocks, so when the two types of rocks collide, oceanic rocks sink into the mantle and are
recycled. A tiny bit of hydrogen escapes from the planet in the solar wind, but not much else.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
6., Hot spots:
, A., Move around rapidly under the plates while the plates sit still.
B., Rise from as deep in the mantle as the coremantle
boundary to the surface of the Earth, bringing up heat
and feeding volcanoes.
C., Are found only under continents.
D., Bring Pepsi from deep in the Earth to Penn State under an exclusive contract negotiated by President
Spanier.
E., Are found only under oceans.
Earthquakes make sound waves that go through the whole Earth, and go slower through hotter, lessdense
rocks. By putting out listening devices called seismometers around the Earth, and listening to the waves from
many earthquakes in many places, scientists can map the hotter regions, and find that towers of hot rock come
up from way deep in the Earth in some places. But, some other hot spots don’t seem to start as deep. The hot
spots don’t seem to move around much, but the lithospheric plates drift around over the hot spots. Hot spots
come up beneath continents and oceans, and can poke through both. But no one has ever found Pepsi in a
hotspot
plume.
, Points Earned:, 1/1
Correct Answer:, B
Your Response:, B
7., Hot spots usually:
, A., Feed basaltic volcanoes (composition similar to sea floor).
B., Feed stratovolcanoes.
C., Are not associated with volcanoes.
D., Feed volcanoes that have especially steep sides on the parts sticking above sea level.
E., Feed andesitic volcanoes (composition similar to continents).
The rising hot rock of hot spots feeds volcanoes. Both sea floor and hotspot
volcanoes come from melting a
little of the verylowsilica
mantle, pulling out the melt, and freezing it, and so are basaltic (lowsilica)
volcanoes.
Note, though, that a few hotspots (such as Yellowstone) are not basaltic, because the basalt has been altered
in getting through the continent. The melt probably started out as something that would make basalt, and
indeed, the Yellowstone hotspot
track includes basaltic lavas such as those at the glorious Craters of the Moon
National Monument. The hotspot
lavas are runny, and spread easily under the air to make volcanoes with
gradual slopes, unlike the steep stratovolcanoes, although the slopes of hotspot
volcanoes are steeper under
water because the water cools the lava so rapidly that it can’t spread far.
, Points Earned:, 1/1
Correct Answer:, A
Your Response:, A
,
8., Look at the picture above. What happened here?
, A., A great volcanic explosion occurred, spreading material across the landscape, and the hole left behind
after the eruption later filled with water.
B