Geosc 10

If all the water that falls on central Pennsylvania's Happy Valley in a year as snow or rain stayed here as water without being used or evaporated, if spread uniformly over the land, it would make a layer about how thick? (Pennsylvania gets about the same amount of precipitation as the average for the world.) A) 3 feet. B) 30 feet. C) 0.03 feet. D) 0.3 feet. E) 0.003 feet.

A) 3 feet. feedback: A typical rainfall supplies about an inch of water, or just under 0.1 foot. 30 feet of rain would be a big storm every day, about equal to the wettest place on Earth, and while sometimes it may seem the rain in Pennsylvania will never end, there really are clear days. 0.3 feet is a mere 3 or 4 rainfalls per year, and is a dry desert. 0.03 feet would be the driest place on Earth, and 0.003 doesn't occur on Earth. 3 feet is a nice number, and is correct.

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) A sharp bend in a river created a whirlpool that carved the hole now filled by a lake. C) An immense marmot named George, shown here, dug the hole. D) 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. E) Death-Valley-type faulting dropped the bottom, making space for the lake; during the Ice Age, Death Valley looked like this, too.

A) A great volcanic explosion occurred, spreading material across the landscape, and the hole left behind after the eruption later filled with water. Feedback: 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 crater of Crater Lake, almost 2000 feet deep and 6 miles across, left by the cataclysmic eruption of Mount Mazama in Oregon.

The pink arrows point to a barrier beach, formed when waves fromthe ocean (on the left) washed away mud and piled up sand, after themud and sand were delivered by the stream flowing in from the upperright. The yellow arrows point to interesting features. How did they form? A) A storm broke through the barrier beach and pushed sand farther inland. B) Beavers dug through the barrier beach and threw the material behind them, forming the yellow-arrowed deposits. C) The beach used to be where the yellow arrows are, but was moved seaward by the river, which flowed over the old beach. D) A sinkhole opened behind the barrier beach, and the yellow-arrowed material slumped into it. E) The stream flowing from the upper right is a braided stream, and the yellow arrows point to levees that keep the stream from flooding.

A) A storm broke through the barrier beach and pushed sand farther inland. Feedback: Barrier beaches are piled up by waves, but especially strong storms often break through the beaches. Some of the sand at such new inlets is moved toward the land, often forming new beach-like deposits such as those indicated by the yellow arrows. Some sand is also often moved offshore into deeper water. The river would have buried or reworked the yellow-arrowed features if the river flowed over them, there is no sign of a sinkhole, and bars in the river can be seen to be lower and elongated, not on top and transverse as the yellow-arrowed features are.

We now know a lot about the big processes that shape the Earth's geology. Which of the following is NOT correct about that knowledge? A) Almost all of the motion of lithospheric plates is vertical, with almost no horizontal motion. B) Most formation of mountains occurs near the edges of the lithospheric plates. C) The lithosphere is broken into a few large plates plus a few smaller ones. D) The upper layer of the Earth, called the lithosphere, is made of plates that float on softer material below. E) Convection occurs in the hot, soft rocks below the lithosphere.

A) Almost all of the motion of lithospheric plates is vertical, with almost no horizontal motion. Feedback: Although there surely is vertical motion, making mountains and subduction zones, most of the motion is horizontal, with plates moving hundreds or thousands of miles.

Most earthquakes: A) Are caused when rocks on opposite sides of a break, or fault, in the Earth's crust move in different directions, and the fault is poorly lubricated, so the rocks along the fault get stuck for a while and bend their neighbors before breaking free and moving. B) Are caused by Diet Coke drinkers kicking Pepsi machines. C) Are caused by "implosion" of minerals taken to great depth in the Earth by tectonic processes. D) Are caused when rocks on opposite sides of a break, or fault, in the Earth's crust move in different directions, and the fault is well-lubricated all the time so the rocks can move freely. E) Are caused when rocks on opposite sides of a break, or fault, in the Earth's crust move in the same direction at the same speed.

A) Are caused when rocks on opposite sides of a break, or fault, in the Earth's crust move in different directions, and the fault is poorly lubricated, so the rocks along the fault get stuck for a while and bend their neighbors before breaking free and moving. Feedback: There may be "implosion" earthquakes, but they are rare. Some breaks in the crust are well-lubricated and don't make earthquakes. If rocks on opposite sides of a break move in the same direction at the same speed, then there will be no relative motion between those rocks, and they won't make earthquakes. But when rocks try to move in opposite directions but are stuck, they bend like springs and then break, shaking things and knocking them down in an earthquake. And Diet Coke drinkers who have not yet had their caffeine are unlikely to be sufficiently agitated to kick the Pepsi machines hard enough to make the larger earthquakes that are observed.

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) Basaltic hot-spot volcanoes such as Hawaii. B) Push-together earthquakes and faults as the subducting slab squeezes the rocks. C) Stratovolcanoes such as Mt. St. Helens, formed by lava flows and explosions form the slab being subducted. D) Piles of sediment scraped off the slab being subducted. E) Andesitic volcanoes such as Crater Lake, fed by melt from the slab being subducted.

A) Basaltic hot-spot volcanoes such as Hawaii.

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) C is slide-past, B is pull-apart, and A is push-together. B) C is pull-apart, B is push-together, and A is slide-past. C) C is push-together, B is slide-past, and A is pull-apart. D) C is push-together, B is pull-apart, and A is slide-past. E) C is slide-past, B is push-together, and A is pull-apart.

A) C is slide-past, B is pull-apart, and A is push-together. Feedback: 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).

In the photo above Dave and Kym are discussing a model of the Waterpocket Fold in Capitol Reef National Park. The Waterpocket probably formed in the same way as the Front Range of the Rockies. This involved: A) Especially warm sea floor in the subduction zone off the west coast rubbed along under western North America and squeezed or wrinkled the rocks, folding them (probably with a push-together fault somewhat deeper under the fold). B) The rocks were dropped along a Death-Valley-type fault. C) The rocks were dropped when salt deposits below were dissolved by groundwater. D) The rocks were wrenched and twisted by a San Andreas-type slide-past fault. E) The rocks were folded by obduction when California docked on the west coast.

A) Especially warm sea floor in the subduction zone off the west coast rubbed along under western North America and squeezed or wrinkled the rocks, folding them (probably with a push-together fault somewhat deeper under the fold). Feedback: We're still arguing about the West, but it is clear that the west-coast subduction zone, which started with old, cold sea floor going down, slowly warmed as the subduction zone and the spreading ridge came closer together. Warmer sea floor would be more buoyant, and so would sink more slowly, or float better. And that would create more friction, squeezing and rumpling with the overlying continent. As the sea floor warmed, squeezed-up/rumpled-up features developed in the West. So we think this makes sense

What probably happened to create the two rocks with the orange surfaces, seen in the center of the above picture from Greenland? A) Expansion from water freezing in the crack wedged the rock apart B) A performance artist painted the rock orange, to signify the coming of deer-hunting season C) A tree root cracked the rock, which killed the tree, so we don't see the tree anymore D) The two pieces of rock with the orange are completely unrelated, and just happened to wind up next to each other E) The rock was recently erupted from a volcano, thrown high in the air, and broke when it hit the surface, as shown by the orange caused by heat from the volcano

A) Expansion from water freezing in the crack wedged the rock apart Feedback: Frost-wedging is probably the most important process in breaking rocks. Tree roots do crack rocks, but in this case, the root almost certainly would have shoved the rocks farther apart, and breaking rocks doesnt kill trees. The broken surface is colored by lichen, which doesnt look much like paint. And if a volcano made the orange, the orange would be on the outside as well.

The glacier shown above: A) Has retreated, because a decrease in snowfall to the accumulation zone (A) or an increase in melting of the ablation zone (B) occurred. B) Has retreated, because a decrease in snowfall to the ablation zone (A) or an increase in melting of the accumulation zone (B) occurred. C) Has advanced, because a decrease in snowfall to the accumulation zone (A) or an increase in melting of the ablation zone (B) occurred. D) Has advanced, because a decrease in snowfall to the ablation zone (A) or an increase in melting of the accumulation zone (B) occurred. E) Has not changed.

A) Has retreated, because a decrease in snowfall to the accumulation zone (A) or an increase in melting of the ablation zone (B) occurred. feedback: Accumulation is a building up, ablation a wearing away or loss. The glacier builds at high elevation (A) and wears away at low elevation (B). And, the halo of moraine around this glacier at low elevation shows that the ice has retreated, so a decrease in snowfall to the accumulation zone or an increase in melting of the ablation zone is indicated.

The interactions at the edges of plates are very important. Which is NOT an interaction that is commonly observed all along the length of one of the edges where two plates meet? A) Hot spot. B) Push-together obduction. C) Push-together subduction. D) Pull-apart. E) Slide past.

A) Hot Spot Feedback: A hot spot pokes through a plate from below, in some small region. All of the others happen at the long edges of plates.

Icebergs float in water and continents float above the mantle because: A) Icebergs/continents are less-dense than the stuff they float in. B) Icebergs/continents are colder than the stuff they float in. C) Icebergs/continents are filled with helium. D) Icebergs/continents are denser than the stuff they float in. E) Icebergs/continents are warmer than the stuff they float in.

A) Icebergs/continents are less-dense than the stuff they float in. Feedback: Flotation and buoyancy are driven by density differences. In general, less-dense objects float higher up than more-dense objects would. Sometimes the density differences are due to temperature, sometimes due to composition. In the case of icebergs, water is denser than ice, so ice floats. Similarly continental crust is less dense than the mantle.

Bigger earthquakes occur less frequently, but a bigger quake releases more energy and does more damage. An interesting question to ask about earthquakes (and about almost anything else!) is whether the increase in energy release and damage done is larger or smaller than the decrease in frequency as one looks at bigger earthquakes. Asked a different way, is most of the damage done by the many little earthquakes or by the few big earthquakes? A) Most of the damage is done by the few, big earthquakes. B) Earthquakes only damage Coke machines, under an exclusive contract with Pepsi. C) Earthquakes don't do any damage, so this is a silly question. D) Most of the damage is done by the many, little earthquakes. E) The drop-off in frequency just balances the rise in energy, so all earthquake sizes contribute equally to global earthquake damages.

A) Most of the damage is done by the few, big earthquakes. Feedback: An increase of 1 in 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 earthquakes are actually very poor at distinguishing the brands of soda dispensed by or advertised on machines.

What is accurate about seismic waves moving through the Earth? A) P-waves (also called push-waves or sound waves) move through both solids and liquids. B) P-waves (also called push-waves or sound waves) move through neither solids nor liquids. C) P-waves (also called push-waves or sound waves) move through solids and all liquids except Diet Pepsi. D) P-waves (also called push-waves or sound waves) move through liquids but not solids. E) P-waves (also called push-waves or sound waves) move through solids but not liquids.

A) P-waves (also called push-waves or sound waves) move through both solids and liquids Feedback: P-waves go through liquids and solids, because you can squeeze and release a liquid or a solid—push here and it squeezes a bit, which squeezes what is next to you... and on in a wave.

The stiff basaltic rocks of the sea floor are bent as they enter subduction zones. This means that: A) Subduction zones produce sea-floor trenches, which may be filled with water or with sediment washed from nearby land. B) Erosion of continents by rivers near subduction zones produces deep troughs that include the deepest water in the ocean. C) Subduction zones produce Death-Valley-type down-faulted spreading valleys, which form the deepest parts of the ocean. D) Bending of sea-floor rocks at subduction zones produces high ridges, such as the coast ranges of California. E) Bending of sea-floor rocks near the subduction zone of Oregon and Washington produced a deep trench, which has been filled with discarded Microsoft Windows CDs, thrown away by people sick of all the viruses.

A) Subduction zones produce sea-floor trenches, which may be filled with water or with sediment washed from nearby land. Feedback: As the rocks are bent entering a subduction zone, a trench forms. Trenches are sometimes water-filled, but if close to a continent, materials eroded by rivers or glaciers may fill the trenches. There probably are a few Windows CDs off Washington and Oregon, but not enough to fill the trench. Erosion by rivers doesn't go below sea level (except very rarely, and then only down to close to the bottom of Death Valley, still not very deep).

What happens to most of the water that falls as rain on central Pennsylvania's Happy Valley each year (or any similar place, such as Washington, DC or other places with trees)? A) The biggest amount is re-evaporated, mostly through trees, and most of the remainder soaks into the ground and then flows through the ground to streams. B) It is used in soft-drink bottling plants. C) The biggest amount falls directly on streams, with mosts of the remainder evaporated especially from trees. D) The biggest amount soaks into the ground and then flows through the ground to streams, and most of the remainder flows directly over the surface to streams. E) The biggest amount is re-evaporated, mostly through trees, and most of the remainder flows directly over the surface to streams.

A) The biggest amount is re-evaporated, mostly through trees, and most of the remainder soaks into the ground and then flows through the ground to streams. feedback: Water gives life, and life is very good at using water. When their leaves are out, trees use almost all the rain that falls, and tree roots reach down into the ground and pull up some of the water from cold-season rain and snowmelt. An important amount of water does soak into the ground and flow to streams (maybe 1/3 of the total), but plants still get the majority. The amount of water that flows across the surface is increasing as we pave the landscape, but most of the land is not paved, and flow across natural surfaces to streams is small. Streams are tiny, so direct rainfall into them is small. And soft-drink plants use only a tiny bit of water compared to total rainfall.

The big W is in ocean water, while the little w is in water in a bay cut off from the ocean by the bar indicated by the pink dashed arrow. A stream flows toward the bay along the blue arrow, and coastal bluffs are indicated by the dashed yellow arrow. What probably happened here? A) The low bluffs show that erosion has been occurring as waves hammer the shore, and the bar shows that longshore transport is moving the sediment from that erosion along the shore. B) The low bluffs show that the land is being raised by tectonic processes, which has allowed the ocean to flood over the bar and make the bay. C) The Monterey Bay aquarium built the bar to isolate the bay as a holding tank for the narwhals to be used in their new exhibit. D) A sinkhole opened behind the beach, and the stream slumped into the hole, leaving the bar. E) The low bluffs show that the land is being lowered by tectonic processes, which has formed the bar and allowed the ocean to flood over the bar and make the bay.

A) The low bluffs show that erosion has been occurring as waves hammer the shore, and the bar shows that longshore transport is moving the sediment from that erosion along the shore. feedback: Longshore drift is important, and moves much sediment. The greater width of the beach across the mouth of the stream than nearby shows how far waves can go; adjacent to the stream, the waves must cross the beach during storms and batter the bluffs, making sediment that feeds the longshore drift. If uplift were occurring, it would have dried the bay, and if subsidence were occurring, the bar would have been moved underwater. Narwhals would be great in an exhibit, but the aquarium hasn't been here.

At Cade's Cove in the Great Smoky Mountain National Park, there is an unusual arrangement of rocks where older rocks are sitting on top of younger rocks, though neither layer has been overturned. This is because: A) The older layer was thrust over the younger layer by the forces of obduction. B) George the Marmot did it. C) The younger layer was injected as molten material under the older rock and then solidified. D) The younger layer subducted under the older layer.

A) The older layer was thrust over the younger layer by the forces of obduction Feedback: The Great Smokies are an example of obduction, as are the Ridge-and-Valley mountains of the folded Appalachians, which include Penn State's University Park campus. However, up here the rocks were "rumpled up" but down in Cade's Cove, one set of rocks was thrust over another resulting in older rocks riding over younger rocks.

The Landsat above image from NASA shows Cape Cod, Massachusetts. The short yellow arrow indicates sand deposits at Monomoy Island, a great place for bird-watching. The long pink arrow indicates underwater sand deposits. The dotted blue arrow points to the great Outer Beach of the Cape. Based on material presented in this class, what is going on? A) The outer beach (dotted blue) is losing sand to Monomoy (short yellow), which is losing sand to the undersea bars (long pink), which are losing sand to deeper water, as the Cape slowly shrinks. B) The outer beach (dotted blue) is losing sand to Monomoy (short yellow), which is growing from this extra sand and from sand brought up by storms from the underwater bars (long pink), as the Cape grows overall. C) The ocean is "mining" sand from the underwater bars (long pink) and adding that sand to Monomoy (short yellow), which is then eroded to supply sand to the Outer Beach (dotted blue), as the Cape grows overall. D) The outer beach (dotted blue) is losing sand to deep water to the east, while Monomoy (short yellow) is growing as sand is brought up by storms from the underwater bars (long pink), as the Cape overall maintains the same size. E) All of the arrows actually indicate piles of peripherals lost by wintertime nudists sunbathing on the Cape's beaches.

A) The outer beach (dotted blue) is losing sand to Monomoy (short yellow), which is losing sand to the undersea bars (long pink), which are losing sand to deeper water, as the Cape slowly shrinks. feedback: The blue-arrowed Outer Beach is eroding, losing some sand to the yellow-arrowed Monomoy Island—a remarkable birding spot—and some sand to the pink-arrowed underwater bars, which lose sand to deeper water—the Cape is losing ground. Furthermore, the Cape is losing ground much faster than nudists are losing peripherals.

Dr. Alley once helped a Grand Canyon ranger answer a tourist's question: "Why is the Canyon wider at the top than at the bottom?" The tourist had their own favorite theory. Based on the materials that have been presented to you've in this class, what geologically accepted answer would Dr. Alley and the ranger have given the tourist? A) The river cuts down, and that steepens the walls of the canyon, which fall, topple, slump, creep or flow into the river to be washed away, thus widening the canyon above the river. B) The bulldozer that made the canyon was wearing out its blade as it dug down. C) The river used to be much wider because it was not steep, and water spreads out when running slowly (a little tap feeds a big bathtub...); then, as the Rockies were raised, the river steepened and narrowed, so it used to cut a wide canyon and now cuts a narrow one. D) The canyon is really the same width at the top as at the bottom, but the well-known "optical illusion" of distant things appearing smaller causes it to look as if the canyon is narrowing downward. E) The river used to be much wider before the desert formed, and so cut a wide canyon, but the river has narrowed as the drying occurred, and now cuts only a narrow canyon.

A) The river cuts down, and that steepens the walls of the canyon, which fall, topple, slump, creep or flow into the river to be washed away, thus widening the canyon above the river. Feedback: The tourist suggested that the river has gotten narrower over time. Dr. Alley asked the tourist whether he would ever consider going out on a particular narrow pillar of rock (already teetering dangerously and separated from the walls of the canyon by a huge crack) with a few hundred of his closest friends, and jumping up-and-down vigorously. Predictably, the tourist said "of course not, it might fall over." Dr. Alley then pointed out the many places where rocks clearly had fallen off the cliffs and moved downhill, at which point the tourist quickly switched his opinion to the "down-cutting" river explanation, with the ranger thoroughly enjoying the show

Dave Janesko is explaining the great Sevier Fault to Dr. Alley and the CAUSE class. [See image: UNIT 2.1] 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 pull-apart fault to lie next to the red rock. B) The scratches are nearly vertical, because the black rocks were pushed up from below along a push-together fault to lie next to the red rocks. 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 slide-past fault. E) The scratches are all horizontal, because the red rocks moved over the black rocks in a landslide.

A) The scratches are nearly vertical, because the black rocks were dropped down along a pull-apart fault to lie next to the red rock. Feedback: 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. The scratches are not too far from vertical, made as the rocks dropped down.

Soil is produced by weathering of rocks. In the natural state of affairs, on a hillside covered by soil: A) The soil thickness tends to a nonchanging value as production is balanced by removal, but you may have to watch for a while, as sometimes production may go faster and sometimes removal may go faster. B) The soil thickness never changes over time; a perfect balance is achieved between soil production and removal so no matter how long you wait or when you measure, the thickness will be the same. C) The soil is mainly produced by human pets. D) The soil layer gets thinner and thinner over time as gravity and streams remove older soils. E) The soil layer gets thicker and thicker over time as weathering breaks down more rocks.

A) The soil thickness tends to a nonchanging value as production is balanced by removal, but you may have to watch for a while, as sometimes production may go faster and sometimes removal may go faster. Feedback: Naturally, there is a balance between production and removal of soil over large areas and long times, but at any moment in a particular place, production and removal may be out of balance, as during a fast-moving landslide or when a marmot is digging a new hole. Human pets (including orange-and-white Coral and gray Prancer Alley, seen here in a group hug with Eeyore), do affect things but are not major sources of soil.

The age of rocks near a sea-floor spreading ridge can accurately be described as: A) The youngest rocks are near the ridge, and the rocks get progressively older as you go away from the ridge in both directions. B) The oldest rocks are to the west of the ridge, and the rocks get progressively younger as you go eastwards. C) The oldest rocks are near the ridge, and the rocks get progressively younger as you go away from the ridge in both directions. D) All rocks everywhere are the same age. E) There is no pattern in age: sometimes the rocks at the mid ocean ridge are older than the rocks on either side, sometimes younger.

A) The youngest rocks are near the ridge, and the rocks get progressively older as you go away from the ridge in both directions. Feedback: At sea-floor spreading ridges, hot magma rises up, cools and solidifies. These rocks then split and move apart as yet more magma rises, cools and solidifies. Over time, the rocks are moved great distances (tens or hundreds of miles) from the spreading ridges. The rocks close to the ridges were deposited recently (they are "young"), but the rocks far from the ridge were deposited long ago and then moved away slowly (they are "old").

Hot spots are important geological features. What is accurate about hot spots? A) They are rising towers of hot rock, perhaps from as far down as the core-mantle boundary, bringing heat up to feed volcanoes. B) They feed volcanoes that grow up from the sea floor, but are never found breaking through continents. C) They are rapidly-moving features, zipping along beneath the nearly stationary plates above to make lines of volcanoes. D) They provide the caffeine consumed during all-night arguments in Washington. E) They feed volcanoes that form on continents, but never feed volcanoes that grow up from the sea floor.

A) They are rising towers of hot rock, perhaps from as far down as the core-mantle boundary, bringing heat up to feed volcanoes. Feedback: Earthquakes make sound waves that go through the whole Earth, and go slower through hotter, less-dense 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 coffee in a hot-spot plume.

The cartoon above illustrates a specific geologic process. In which of the additional images can the same geologic process be seen? (red and yellow car running into each other)

Answer/feedback: The folded Appalachians, including the region of central Pennsylvania around Penn State's University Park campus, shown in the satellite image here, formed when Africa and Europe collided with the Americas, much as the two cars in the picture collided. Death Valley, Crater Lake, and George the Immense Marmot record different processes.

In 2005, Hurricane Katrina brought a storm surge that overtopped the levees and flooded New Orleans, causing over 1400 deaths and perhaps $100 billion in damages. This flooding of New Orleans from a big storm was: A) A disaster that humans made much worse by causing massive sedimentation that raised the whole Mississippi Delta above the surface of the Gulf of Mexico, so that the storm waves could use the Delta as a ramp to jump easily into the city. B) An event that scientists had warned about for decades, based on the known size of hurricanes, and the sinking of the city and the Delta. C) An event proving that if you drive your Chevy to the levee, it causes a hurricane to form. D) An "act of nature" that no one could have foreseen; these things just happen. E) An event that proves that civil authorities are so good at planning that you never need to worry about dangers from any weather events in the future.

B) An event that scientists had warned about for decades, based on the known size of hurricanes, and the sinking of the city and the Delta. feedback: Scientists and planners did not know exactly when a big hurricane would hit New Orleans and threaten the city, but serious assessments had consistently highlighted the possibility for decades. The failures at New Orleans happened despite the fact that Katrina was NOT the "Big One"—on a scale of 1-5, Katrina was a 3 when it made landfall.

Tsunamis: A) Are caused by earthquakes only. B) Are caused by earthquakes, undersea volcanic eruptions, or anything else that displaces a lot of water in a hurry. C) Are caused by changes in the rate of Earth's rotation. D) Are most commonly caused by whale flatulence. E) Are caused by especially large tides, earning them the nickname "tidal wave".

B) Are caused by earthquakes, undersea volcanic eruptions, or anything else that displaces a lot of water in a hurry. Feedback: Throw a rock in the water, kick your foot in the water, swim in the pool, or even emit flatulence in the water, and you'll see one thing all have in common: they make waves. Earthquakes, volcanic eruptions, landslides, or meteorite impacts in the ocean can make waves big enough that we call them "tsunamis".

A glacier flowing down the side of a mountain has come into balance with the climate. Then, a climate change occurs, so that melting exceeds snowfall on the glacier. The glacier will: A) Grow until a new balance is reached. B) Continue flowing down the mountain, but shrink until a new balance is reached or until the ice disappears (of course, it must quit flowing as it disappears!). C) Continue flowing down the mountain, and shrink until a new balance is reached, without ever shrinking until the ice disappears. D) Flow back up the mountain to reach a new balance. E) Grow until if finds a marmot colony to have a chat with.

B) Continue flowing down the mountain, but shrink until a new balance is reached or until the ice disappears (of course, it must quit flowing as it disappears!). feedback: Ice flows down its surface slope, and will continue to do so even if shrinking. Eventually after mass loss starts, either a new balance is reached after the warm toe of the glacier is lost, or else the glacier disappears. And glaciers have not been observed conversing with marmots.

Look at the picture above, from the coast of Olympic National Park. What happened here? (pocket knife under rocks) A) 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. 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) Glaciers coming down from the high peaks of Olympic National Park ground over the surface of the rock, carving the grooves we see. D) The pocket knife was flushed out of an airline toilet by an absent-minded geologist. E) 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. Feedback: 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.

As water from rain soaks through the soil, the water typically: A) Gains Diet Pepsi from the air and loses it in the soil, becoming a strong electrolyte. B) Gains carbon dioxide (CO2) from the air and then gains more carbon dioxide in the soil, becoming more acidic. C) Gains humic compounds from the air and more from the soil, becoming a strong base. D) Neither gains nor loses carbon dioxide (CO2) in the air or the soil. E) Loses carbon dioxide (CO2) to the air and then to plant roots, becoming more basic.

B) Gains carbon dioxide (CO2) from the air and then gains more carbon dioxide in the soil, becoming more acidic. Feedback: CO2 is fairly soluble in water. Rain picks up some in the air, becoming slightly acidic. Lots of things living in the soil emit carbon dioxide, and soils contain a lot of carbon dioxide that helps make water more acidic. Humic compounds are picked up from soil by water, and make the water more acidic.

Most U.S. beaches are shrinking or encroaching on the land rather than growing or moving seaward, so the land of the U.S. is getting smaller, not bigger. Causes include: A) Dams on rivers have increased sediment delivery to the beaches. B) Global sea level is rising, covering more land. C) Global sea level fell as the ice-age ice sheets grew, and this caused rivers to deliver much sediment to the coast. D) Local regions are rising as fluid injection wells used for waste disposal bulge up the land in many places. E) Global sea level fell as the ice-age ice sheets grew, exposing sand to the attack of large waves during winter storms, so beaches are now being removed.

B) Global sea level is rising, covering more land. Feedback:As sea level rises, beaches are pushed landward unless something happens to offset this tendency. Global sea level fell way back in time (from about 110,000 years ago to about 20,000 years ago), but that isn't having much effect on coasts any more. And if the ground were rising from injection wells, then the land would be getting bigger, not smaller.

During the most recent ice age: A) Ice from Canada advanced down the Mississippi to near the Gulf of Mexico, helping build the Mississippi Delta. B) Ice from Canada advanced across the Great Lakes and into the northern states of the US, but not farther. C) Ice from Canada advanced to the northern shore of the Great Lakes, but not farther. D_ Ice from Canada advanced to the southern edge of the Great Lakes, hollowing them out, but didn't go any farther. E) Ice from Canada advanced into Mexico.

B) Ice from Canada advanced across the Great Lakes and into the northern states of the US, but not farther. feedback: This is just a fact of geography; the ice came out of the Great Lakes and somewhat farther, but not greatly so.

Most commonly, a hot-spot volcano: A) Is mostly andesitic in composition. B) Is basaltic in composition. C) Is lower in silica than basalt, more like the mantle from which the hot-spot lava comes. D) Is andesitic in composition, and shaped like a Pepsi can, with vertical sides below sea level. E) Is richer in silica than andesite.

B) Is basaltic in composition. Feedback: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.

These two pictures are from Hawaii Volcanoes National Park, on the flanks of Kilauea Volcano. How are pictures I and II related? A) 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. 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 mined out by the Park Service because it is softer, making visitor-entertaining 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 dissolved more easily by acidic groundwaters because it froze later, leaving caves such as the one shown in I. E) 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. Feedback: 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.

What tectonic setting is primarily responsible for producing Crater Lake? A) Pull-apart. B) Push-together obduction. C) Hot-spot. D) Push-together subduction. E) Slide-past.

B) Push-together obduction. Feedback: Crater Lake, the hole left by the cataclysmic eruption of Mt. Mazama, sits above a subduction zone, where one tectonic plate goes below another as they come together.

What tectonic setting is primarily responsible for producing Olympic National Park as well as the hills on which San Francisco is built? A) Hot-spot. B) Push-together subduction. C) Push-together obduction. D) Slide-past. E) Pull-apart.

B) Push-together subduction. Feedback: The rocks of Olympic and San Francisco were scraped off the downgoing slab of the subduction zone.

What happened in the picture above? A) Divers have built the mud piles to slow down the river water and protect endangered clams that live along the coast. B) Rivers have delivered sediment to the sea, forming deltas that built up as they built out so that they still slope slightly downhill toward the sea. C) A certain financially ailing airline that flies to Cincinnati and then Atlanta built this from thrown-out beverage cups as an advertisement. D) Rivers have delivered sediment to the sea, forming flat-topped deposits called deltas. E) Turbulence where the rivers enter the sea has caused suspended sediment in the seawater to flocculate and settle, forming the deposits seen on the right.

B) Rivers have delivered sediment to the sea, forming deltas that built up as they built out so that they still slope slightly downhill toward the sea. feedback: Two deltas have formed where streams carry sediment from the hillside into the fjord in South Greenland. The main source of sediment is the streams from the land, not suspended sediment already in the sea water. And the deposits cannot be purely flat-topped, or the rivers would not flow across to get to the sea water in the fjord. Mollusks do live along the coast but are not being protected by intrusive changes to the coastline, nor do enough people visit here to be worth advertising Delta Airlines.

Sandy beaches: A) Were all produced by deposits of glaciers. B) Shrink if the sand supply from rivers or coastal erosion is smaller than the sand loss to deep water, and grow if sand supply exceeds the sand loss, remaining in balance if sand supply equals sand loss. C) Are all doomed as soon as global warming causes sea level to rise by more than a few millimeters. D) Are underlain by vast aquifers full of Diet Pepsi. E) Always grow over time because big winter waves bring more sand from deep water to the shore than the smaller summer waves can take back out to deep water.

B) Shrink if the sand supply from rivers or coastal erosion is smaller than the sand loss to deep water, and grow if sand supply exceeds the sand loss, remaining in balance if sand supply equals sand loss. feedback:

A glacier does flow "downhill". Which is correct about the hill? A) The glacier flows from where snowfall is high to where snowfall is low; the "hill" is the big clouds in the atmosphere that supply the snow. B) The glacier flows from where its upper surface is high to where its upper surface is low, and thus flows down the hill of the ice surface. C) The glacier flows from where bedrock is high to where bedrock is low, and thus flows down the bedrock hill. D) The glacier flows from where Hank Hill lives to where Homer Simpson lives, and thus from Texas to Springfield, wherever that is. E) The glacier flows from north to south; we all know that maps have north at the top and south at the bottom, so this is the "hill".

B) The glacier flows from where its upper surface is high to where its upper surface is low, and thus flows down the hill of the ice surface.

Stephanie and Topher are standing next to the Colorado River in the Grand Canyon.What can be said of the water here? A) The river is really filled with 7-UP, hence the green color. B) The river was naturally muddy, but has been made clear because most of the sediment is settling out in the reservoir behind the dam upstream. C) The river water is kept clear by the Park Service to keep the trout healthy. D) The river water is naturally clear, fed by snowmelt from the Colorado Rockies. E) The river was cleaned up briefly by the Park Service to help Stephanie and Topher in their filming.

B) The river was naturally muddy, but has been made clear because most of the sediment is settling out in the reservoir behind the dam upstream. feedback: Native species that lived in the muddy waters are now in danger of becoming extinct, because the clear water released from the dam makes those fish too easy for predators to see.

What is accurate about the planet's climate system? A) The wind blows because of marmot flatulence. B) The wind blows because heating near the equator drives convection cells in the atmosphere, and the winds appears to curve to the left or right over the surface of the planet because of friction produced by the spherical planet's rotation beneath the atmosphere. C)The wind blows because heating near the poles drives convection cells in the atmosphere, and the winds appear to curve to the left or right over the surface of the planet because of friction produced by the spherical planet's rotation beneath the atmosphere. D) The wind blows because heating of the poles drives convection cells in the atmosphere, and the winds appear to curve to the left or right over the surface of the planet because of the planet's the planet is spherical shape. E) The wind blows because heating near the equator drives convection cells in the atmosphere, and the winds appear to curve to the left or right over the surface of the planet because of the planet's spherical shape.

B) The wind blows because heating near the equator drives convection cells in the atmosphere, and the winds appears to curve to the left or right over the surface of the planet because of friction produced by the spherical planet's rotation beneath the atmosphere. Feedback: Heating near the equator causes pressure differences that drive the winds. On a rotating body, whether a flat merry-go-round or a spherical Earth, the rotation causes flows to curve. And very very very little of the wind is traceable to marmots.

The ptarmigan and the marmot have something in common, other than being cute. What is it? A) They both are hyper-flatulent amphibians (from "amphi" for "both"). B) They both are standing on glacially eroded surfaces. C) They are both standing on glacial deposits. D) They both are standing on aretes. E) They both are standing on special glacial deposits called moraines.

B) They both are standing on glacially eroded surfaces. feedback: The carbon-based bird, top, and the carbon-based mammal, bottom, would be unhappy if you accused him of being a silicon-based flatulent amphibians. Moraines and other glacial deposits are composed of small pieces, including till with pieces of many sizes. The striated, polished granites under these cold-climate critters were eroded by glaciers.

The mountain range that contains the folded Appalachians, including Mt. Nittany near Penn State's University Park Campus, and the Great Smoky Mountains, was raised to high elevation primarily: A) When Death Valley opened, squeezing the east coast. B) When the proto-Atlantic ocean closed, at a push-together boundary. C) When the Atlantic Ocean formed, at a pull-apart boundary. D) When a subduction zone formed under Oregon, rumpling the rocks to the east. E) When a hot spot erupted under the east coast, and the surrounding rocks slid down the hill it made and rumpled while sliding.

B) When the proto-Atlantic ocean closed, at a push-together boundary. Feedback: Run a car into a brick wall and the front of the car is crunched and bent. Fly over the folded Appalachians and you'll see the same pattern. There was a little Death-Valley-type uplift next to regions of down-dropping to the east of the Appalachians when the pull-apart happened, but the style of the Appalachians doesn't look like Death Valley, and the mountains were already here when the pulling apart started. We can see that the rumpling from the subduction zone in Oregon extends only 100 miles or so in from the coast, and even the Rockies required a special explanation as to why they are so far inland; the Appalachians are too far away to have been affected by subduction under Oregon. We can see that the Appalachians don't make a circle around a hot spot; they make a long belt parallel to the east coast. The Appalachians are way older than Death Valley, and with the Great Plains in-between, it is clear that the influence of Death Valley does not extend to rumpling rocks near the east coast.

The ridge left behind by a glacier that outlines where the glacier had been is called: A) An arête, composed of till (which is unsorted) and outwash (which is sorted). B) A cirque, composed of till (which is sorted) and outwash (which is unsorted). C) A moraine, composed of till (which is unsorted) and outwash (which is sorted). D) A moraine, composed of till (which is sorted) and outwash (which is unsorted). E) A horn, composed of till (which is unsorted) and outwash (which is sorted).

C) A moraine, composed of till (which is unsorted) and outwash (which is sorted). feedback: The beautiful moraines of Cape Cod, Long Island, Moraine State Park in Pennsylvania, Kettle Moraine State Park in Wisconsin, and elsewhere include unsorted till and sorted outwash.

When we speak of the Mississippi Delta, most people mean some interesting region in Louisiana with good music and seafood. Geologically, however, the Mississippi Delta is: A) A great trench eroded by the Mississippi River from near St. Louis, Missouri to the Gulf of Mexico, causing earthquakes to occur at the tip of this trench near St. Louis, Missouri. B) A small trench eroded by the Mississippi River from near Baton Rouge, Louisiana to the Gulf of Mexico. C) A river-built deposit that is several miles thick at its thickest point, and extends from near St. Louis, Missouri to the Gulf of Mexico. D) A river-built deposit that is almost a mile thick at its thickest point, and extends from near Baton Rouge, Louisiana to the Gulf of Mexico. E) A giant pile of spit-up Yoo Hoo.

C) A river-built deposit that is several miles thick at its thickest point, and extends from near St. Louis, Missouri to the Gulf of Mexico. feedback: Amazing as it may seem, the Mississippi has been taking the debris from the vast area from the Rockies to the Appalachians, and dumping that debris into the Gulf of Mexico, building a pile of sediment that is miles thick in places and extends from St. Louis to the Gulf. The mud has filled an old crack in the continent from when the Atlantic and Gulf of Mexico opened, but the mud doesn't stop the earthquakes that occasionally occur near the tip of the crack. And as for the Yoo Hoo, Yuck!

Regions with mountain glaciers that experience much surface melting in the summer typically are eroded: A) At the same rate as regions with streams but no glaciers. B) At the same rate that natural rainfall dissolves granite. C) At a faster rate than regions with streams but no glaciers. D) Not at all; no erosion occurs in typical regions with melting glaciers. E) At a slower rate than regions with streams but no glaciers.

C) At a faster rate than regions with streams but no glaciers. feedback: Yosemite Valley, Glacier National Park and other glaciated regions still bear the unmistakable marks of glaciers despite more than 10,000 years of modification by streams. Glaciers experiencing melting change the landscape faster than streams do.

Convection occurs: A)In solids only. B) Because hotter things are more dense and tend to sink. C) Because hotter things are less dense and tend to rise. D) In liquids only. E) Because hotter things are more dense and tend to rise.

C) Because hotter things are less dense and tend to rise. Feedback: Almost everything expands from heating, taking up more space with the same weight and so becoming less dense. Gases, liquids, and sufficiently soft solids can convect if heated from below, with warming of the lower layer causing it to rise.

You place a granite monument in the cemetery to honor one of your ancestors. If your great-great-great-great-...-great grandchildren were to come back and look at the base of the monument, where it is buried in the soil, they likely would find: A) Clays that were produced by weathering then dissolved and washed away with the water in the rain. B) The quartz had all washed away to the ocean, while the feldspar and dark-mineral grains hung around to make soil. C) Clays and rust were produced by weathering, and hung around to contribute to the soil, while soluble ions dissolved and were washed away toward the ocean. D) Soluble ions were produced by weathering, and hung around to help make soil, while clays and rust produced by weathering all washed away rapidly to the ocean. E) No changes whatsoever.

C) Clays and rust were produced by weathering, and hung around to contribute to the soil, while soluble ions dissolved and were washed away toward the ocean. Feedback: Weathering of granite in Pennsylvania or Washington DC or other places where abundant rain falls makes some things (clay, rust, and quartz sand) that stay behind to contribute to soil, and other things (soluble ions) that dissolve and wash away very quickly.

In the picture above, the ice that modified the rock moved: A) From bottom to top; ice often is forced uphill, as seen here. B) Directly from the rock toward the camera. C) From left to right, striating the surfaces the ice reached first and plucking blocks loose from the far sides of bumps. D) From right to left, smashing the front of the rock and then sandpapering the back of the rock smooth. E) From top to bottom; ice flows downhill, and this is the downhill direction.

C) From left to right, striating the surfaces the ice reached first and plucking blocks loose from the far sides of bumps. feedback: Indeed, ice sandpapers and striates the rocks it hits first, and then plucks blocks loose from the other side. And the striae go in the direction that the ice moved.

Weathering attacks a granite in Pennsylvania or Washington, DC, or a similarly rainy place. The feldspar grains in the granite primarily: A) Are loosened from the rock but don't change much, staying in the soil as diamonds, rubies and emeralds. B) Dissolve and wash away quickly and completely, helping grow shells in the ocean while leaving nothing behind in the soil. C) Mostly make clay that stays in the soil for a while, although some chemicals also dissolve and wash away to the ocean. D) Are loosened from the rock but don't change much, which is where we get quartz sand. E) Dissolve and wash away quickly and completely, to react with sea-floor rocks in the ocean, while leaving nothing behind in the soil.

C) Mostly make clay that stays in the soil for a while, although some chemicals also dissolve and wash away to the ocean. Feedback: Feldspar gives up some things that dissolve and wash away, but most of the material stays behind, rearranges its structure, and adds a bit of water, making clay that contributes to soil formation.

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) the same width and depth as it is today C) Narrower and shallower than it is today D) Wider than it is today, with no change in the depth. E) Deeper than it is today, with no change in the width.

C) Narrower and shallower than it is today Feedback: 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. Thus, in the past the valley was narrower and shallower than it is now, and the motions have deepened and widened the valley.

Which ocean is almost entirely encircled by volcanic arcs in a "Ring of Fire": A) "Southern". B) Arctic. C) Pacific. D) Indian. E) Atlantic.

C) Pacific. Feedback: The Andes, the mountains of central America, the Cascades, the Aleutians, Japan, New Zealand and others ring the Pacific in a subduction-zone ring of fire. The Pacific is getting smaller as it is gobbled up in these subduction zones. The Indian Ocean has volcanic arcs to the east, the Aleutians draw an explosive boundary to the Arctic Ocean between the mainland of Alaska and Siberia, there is a little Atlantic subduction-zone volcanism in the Caribbean and far south in the Scotian Arc, and that Scotian Arc contributes to a little subduction-zone volcanism around the "Southern Ocean" that encircles Antarctica, but none of the other oceans is encircled the way the Pacific is.

Serious scientists are studying the effects of volcanoes on climate. A single, large, explosive volcanic eruption affects climate by: A) Making such loud "noises" (shock waves) that the atmospheric circulation is affected for the next years, stopping El Niño. B) Putting so much carbon dioxide into the atmosphere that the climate warms greatly. C) Putting enough particles up to block enough sunlight to cool the climate a degree or two for a year or two. D) Changing the rotation of the Earth a little bit, which changes the weather, stopping El Niño. E) Putting so much Duff Beer into the stratosphere that it puts alcohol vendors out of business.

C) Putting enough particles up to block enough sunlight to cool the climate a degree or two for a year or two. Feedback: The carbon dioxide from volcanoes affects the atmosphere over millions of years, but not nearly enough is put up from one volcano to matter. But the sun-blocking power of volcanic ejecta is well-known. Some people think that we could offset some global warming by "geoengineering" this effect, throwing pollution into the stratosphere to block the sun.

Evidence that there was much more land ice about 20,000 years ago than there is now includes: A) Immense volumes of Diet Pepsi were forced into subglacial aquifers by the weight of the overlying ice, serving as the modern source of all the Diet Pepsi sold. B) Land bearing the unique marks of glaciers is sinking today, while regions just around that land are rising as deep hot rock flows back after being displaced by the glaciers. C) Shells of creatures that lived in the ocean about 20,000 years ago indicate that the ocean water was especially isotopically heavy then. D) River valleys have cut down rapidly over the last 20,000 years, draining coastal embayments. E) 20,000-year-old deceased shallow-water corals occur in growth position far above modern sea level on the sides of oceanic islands.

C) Shells of creatures that lived in the ocean about 20,000 years ago indicate that the ocean water was especially isotopically heavy then. feedback: The land with the unique glacier marks was pushed down by the ice and now is bobbing back up, water returned to the oceans from the melting ice caused sea level to rise so that river valleys were drowned and are filling up with sediment, and so that shallow-water corals were left far below sea level, but taking light water out of the oceans to grow ice sheets causes the remaining waters, and the shells, to be isotopically heavy.

What does the picture below illustrate? A) The equator is hotter because it rotates faster, and the wind heats the surface as it rotates by, just as Dr. Alley can turn his head rapidly and cause heat by friction B) The equator is hotter than the poles because most volcanoes are located near the equator, forced there by the centrifugal force of Earth's rotation, and Dr. Alley exhales hot air from his equatorial nose C) The equator is hotter than the pole because the sun hits the equator directly but the sun hits the pole a glancing blow D) Dr. Alley is undoubtedly the sexiest human being on Earth E) The equator is hotter than the pole because the equator is closer to the sun than the pole

C) The equator is hotter than the pole because the sun hits the equator directly but the sun hits the pole a glancing blow Feedback: Geometry is the main control on equatorial heating. Although the equator is closer to the sun than the pole, the difference is tiny and matters little to the temperature difference between equator and pole. The rotation of the Earth causes winds to turn as they blow over the surface, but does not heat the air. There is no clustering of volcanoes at the equator, and the heat from volcanoes is tiny compared to the heat from the sun. And we are quite confident that several celebrities and politicians believe that they are the worlds sexiest human being, so Dr. Alleys standing cannot be undoubtedly claimed.

On the Richter scale of earthquake intensity: A) A magnitude-8 quake is impossible; nothing that big can occur. B) The ground is shaken twice as much by a magnitude-4 quake as by a magnitude-2 quake. C) The ground is shaken 10 times more by a magnitude-8 quake than by a magnitude-7 quake. D) The ground is shaken 6 times more by a magnitude-6 quake than by a magnitude-1 quake. E) The ground is shaken 10 times more by a magnitude-3 quake than by a magnitude-4 quake.

C) The ground is shaken 10 times more by a magnitude-8 quake than by a magnitude-7 quake. Feedback: 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.

Which is accurate about the Earth? A) The lithosphere and the asthenosphere freeze in the winter to make Pepsi slushees. B) The lithosphere usually flows rather than breaks, and the asthenosphere usually breaks rather than flows. C) The lithosphere usually breaks rather than flows, and the asthenosphere usually flows rather than breaks. D) The lithosphere usually breaks rather than flows, and the asthenosphere usually breaks rather than flows. E) The lithosphere usually flows rather than breaks, and the asthenosphere usually flows rather than brea

C) The lithosphere usually breaks rather than flows, and the asthenosphere usually flows rather than breaks. Feedback: Litho means stone, and the lithosphere is the hard breakable layer, above the softer asthenosphere.

The picture above shows a hillslope in Greenland that is about ½ mile across. The hill slope towards you, so the lowest part of the hill is at the bottom of the picture, and the highest part is at the top of the picture. What is likely to be true? A) The materials on the hillside are moving toward you at a few miles per year. B) The materials on the hillside have never moved. C) The materials on the hillside are moving toward you at an inch or so per year. D) The materials on the hillside are moving toward you at many miles per hour. E) The materials on the hillside are not moving, but moved toward you at a few miles per year during the ice age when such motion was common.

C) The materials on the hillside are moving toward you at an inch or so per year. feedback: The hillslope in Greenland bears the unmistakable signs of creep on permafrost, carrying streams of rocks and bits of tundra downhill at an inch or so per year. Such processes used to occur in Pennsylvania and elsewhere during the ice age, but are still active in Greenland.

Most landslides happen when: A) The unconsolidated materials on hillslopes are dry, so the grains roll easily downhill. B) The unconsolidated materials on hillslopes are paved with blacktop. C) The unconsolidated materials on hillslopes are very wet and thus heavy and slippery, and the water doesn't have to "break" as the grains move. D) The unconsolidated materials on hillslopes are paved with concrete.

C) The unconsolidated materials on hillslopes are very wet and thus heavy and slippery, and the water doesn't have to "break" as the grains move. Feedback: Dry sand can move, but even very dry times on hillsides usually don't cause landslides. But let a hurricane really saturate things, and all heck can break loose. Paving causes lots of changes, but landslides are not usually the result.

A dam is built on a river, forming a reservoir. Over time, this likely will cause the fields of some farmers along the river just upstream of the reservoir: A) To be washed away as the river cuts downward while the extra sediment is deposited below the dam. B) To dry out as the water table falls. C) To be buried by sediment. D) To become saturated with Pepsi. E) To experience no changes.

C) To be buried by sediment. feedback: The stream will slow where it enters the new lake, and so will deposit sediment to form a delta rather than cutting downward or having no change. As the delta builds out into the lake, the upstream end of the delta must build up so that the stream still slopes downward, and this will tend to bury fields upstream. The water table will rise as the lake floods formerly dry regions, but the lake is highly unlikely to contain Pepsi, which has a carefully guarded formula.

You are magically able to map where the sand grains go for over a few years on an east coast beach. MOST of the motion is: A) Toward the shore in the summer, and away from the shore in the winter. B) Along the shore, in the longshore drift. C) Toward and away from the shore with individual waves. D) Toward the shore in the winter, and away from the shore in the summer. E) Into deep water.

C) Toward and away from the shore with individual waves. feedback: A beach sand grain spends most of its time coming in, going out, coming in, going out, and not getting anywhere. A tiny bias exists, such that the in and out will move slightly along the coast, and will cause seasonal changes, and will move some sand to deep water.

In the picture above, Dr. Alley is on the South Rim of the Grand Canyon. What problem with the Canyon is he discussing? A) A dire shortage of Pepsi has developed at the Canyon, forcing people to actually drink water. B) Arizona has raised the tax on well-drilling, and the Park Service is having trouble paying for the water used at the Canyon. C) Water is being pumped out of the ground on the plateau south of the Canyon, and used by humans and evaporated or dumped in streams, so the water does not flow to the springs in the Canyon. D) Human wastes are being dumped on and pumped into the ground, polluting the springs in the Canyon. E) A dire shortage of Pepsi has developed at the Canyon, forcing people to actually drink water, and the people have found they like water.

C) Water is being pumped out of the ground on the plateau south of the Canyon, and used by humans and evaporated or dumped in streams, so the water does not flow to the springs in the Canyon. feedback: Water soaks into the ground on the plateaus beside the canyon, seeps down to hit a rock layer that blocks the flow, and flows along that layer to feed beautiful and biologically important springs in the Canyon. Pumping water out of the ground on the plateaus to use for humans generally allows the water to evaporate (say, from the grass of a golf course) or run down a stream (say, below a sewage treatment plant), so the water doesn't flow through the ground to the springs.

Near Aaronsburg, PA, a company wanted to start a limestone quarry, and planned to pump lots of water out of the ground to make things fairly dry near the quarry so it wouldn't fill with water. Concern was raised—would this affect the nearby trout streams? So, a little harmless dye was placed in a sinkhole next to the proposed quarry, and a fire-engine pumper added a lot of water to the sinkhole. How long did it take, or will take, for the dye to reach the trout stream? A) A few centuries. B) A few thousand years. C) Never, because all sinkholes drain to Michigan. D) A few hours to days. E) Never, because sinkholes don't drain to trout streams.

D) A few hours to days. feedback: The dye showed up in a few hours, and the quarry was not excavated. Sinkholes often connect directly and quickly to underground caves or big cracks, and thus to streams, allowing rapid drainage. There are rock units that would hold their water for centuries or millennia, but such units have small spaces, not caves and sinkholes. Local sinkholes do drain to trout streams, and Michigan has to make their own water pollution because water pollution from Pennsylvania does not reach them. (Fun thing to do if you're bored: fit this question into the Michigan fight song.)

The above picture shows: A) A permafrost soil-creep lobe, which is generally coming toward you, moving in the opposite direction indicated by the arrow. B) A glacier, which has quit flowing and is wasting away in response to global warming. C) A glacier, which is generally flowing away from you, carrying rocks to smear them against the ridges as the glacier makes the mountains bigger; you can see where the black stripe under the yellow arrow curves around to smash against the rock. D) A glacier, which is generally flowing toward you, carrying rocks picked up from the ridges; the yellow arrow points up one of the stripes of rock, and you can follow the stripe to the ridge where the rocks started. E) A permafrost soil-creep lobe, which is generally moving away from you, moving in the direction indicated by the arrow.

D) A glacier, which is generally flowing toward you, carrying rocks picked up from the ridges; the yellow arrow points up one of the stripes of rock, and you can follow the stripe to the ridge where the rocks started. feedback: The glacier picks up rocks from ridges, and carries those rocks along to eventually dump those rocks in moraines. The ice is flowing down its surface slope toward you.

Death Valley National Park preserves the lowest-elevation, hottest piece of the U.S. The park is fascinating for many reasons. What is accurate about volcanoes and Death Valley National Park? A) Death Valley has special Diet Pepsi volcanoes, and the Pepsi Corporation was founded to run the 20-mule teams that hauled the Diet Pepsi out of the valley, to be bottled in California and shipped around the world. B) Death Valley had active volcanoes millions and millions of years ago—heck, most places had volcanoes at some time—but the volcanoes have been dead for millions of years. C) There are no volcanoes in Death Valley; even though the valley has hot air, the rocks beneath are far too cool to support volcanoes. D) Although no volcanoes are actively erupting at the moment this is being typed, eruptions have occurred in the geologically recent past (the most recent centuries or millennia), demonstrating the presence of hot rock at shallow depth beneath the valley. E) When the ice-age ice sheets grew into Death Valley, volcanoes melted them, which is why Death Valley had a lake then; but, the volcanoes all died more than 10,000 years ago when the ice age ended.

D) Although no volcanoes are actively erupting at the moment this is being typed, eruptions have occurred in the geologically recent past (the most recent centuries or millennia), demonstrating the presence of hot rock at shallow depth beneath the valley. Feedback: Death Valley, and many of the surrounding parts of Nevada and California, have experienced geologically recent volcanic activity. This is one of the problems facing the plan to put nuclear waste in an underground repository in Nevada and leave that waste—are we sure that a volcano won't erupt through the repository? There has not been enough lava erupted to fill the valley, however, nor do volcanoes erupt Diet Pepsi (although you can make a nice volcano model by quickly popping the top of a hot, shaken can of pop).

In the photo above, the letters A and B are in bowl-shaped features in east Greenland. If you were to walk along the ridge just below the yellow line, you would be balanced on a knife-edged ridge between the two bowls. That ridge is called: A) A moraine, bulldozed up by the glaciers that hollowed out the bowls. B) A giant alien toilet, proof that we are visited by beings from another planet, but only evident from the air such as seen here. C) A cirque, a bowl gnawed into a mountain at the head of one glacier. D) An arête, left between the bowls formed by two glaciers that gnawed into the mountain from either side. E) A blockfield, formed by freeze-thaw processes, which would cause you to twist your ankle if you walked along it.

D) An arête, left between the bowls formed by two glaciers that gnawed into the mountain from either side feedback: This is indeed an arête, between two cirques. The strong layering of the rock material is suggestive of bedrock, not loose pieces as seen in moraines and blockfields. (This is basaltic bedrock from the breakup that formed the Atlantic.) And whoooo, what would the alien use for TP???

The picture above shows Telescope Peak, towering above Death Valley.The straight edge of the alluvial fan in the foreground is: A) An earthquake fault, where the mountains are being shoved upward and over the top of the valley. B) Something the design team put in using Photoshop, because nothing in nature could be so straight. C) The excavation for the shoulder of the scenic Zabriskie Point Highway along the west side of Death Valley National Park, which, along with Trail Ridge Road in Rocky Mountain, Going-to-the-Sun Road in Glacier, and the Windows Highway in Zion, is one of the four most famous drives of the national parks. D) An earthquake fault, where the valley has dropped relative to the mountains. E) An earthquake fault, from long ago in geological time when tectonic processes still affected Death Valley.

D) An earthquake fault, where the valley has dropped relative to the mountains. Feedback: The valley is still dropping along earthquake faults as the mountains move away from the valley center. Straight-line faults really do exist. The "famous" Zabriskie Point Highway does not exist, although you can drive out there; given the vast flat expanse of the bottom of Death Valley, the park service would not have excavated to build a highway, choosing instead to save a few tens of millions of dollars by just putting the highway on the flat valley floor.

Air moves in from the Pacific, over the Sierra Nevada (a mountain range), and down towards Death Valley. What happens? A) As the air rises up the Sierra, the air is compressed, evaporating clouds and warming by 5 degrees F per thousand feet upward. B) As the air rises up the Sierra, the air expands, making rain and snow, and cooling by 5 degrees F per thousand feet upward. C) As the air rises up the Sierra, the air is compressed, making rain and snow, and warming by 5 degrees F per thousand feet upward. D) As the air rises up the Sierra, the air expands, making rain and snow, and cooling by 3 degrees F per thousand feet upward. E) As the air rises up the Sierra, the air cools, making clouds that rain Diet Pepsi on unsuspecting marmots beneath.

D) As the air rises up the Sierra, the air expands, making rain and snow, and cooling by 3 degrees F per thousand feet upward. Feedback: If clouds and rain are not forming, rising air cools by about 5 degrees F per thousand feet upward. But, condensing water to make clouds and rain releases the heat that was stored when the water evaporated, so air that is making clouds and rain doesn't cool as much as dry air. The cooling of air making clouds and rain is about 3 degrees F per thousand feet upward.

The above picture shows ocean in the upper right, a beach, andland (lower left). The red dashes trace the crest of a wave. Wavesmove perpendicular to their crests. What principle is illustrated by the picture? A) Because waves go faster in shallower water, waves move primarily along the beach, causing longshore motion of sediment. B) Because waves move slower in shallower water, waves turn and move exactly toward the beach. C) Because waves go faster in shallower water, waves turn and move almost directly towards the beach, but the little bit of along-beach motion remaining drives longshore transport. D) Because waves go slower in shallower water, waves turn and move almost directly towards the beach, but the little bit of along-beach motion remaining drives longshore transport. E) The rotation of the Earth causes wave crests to be curved as they approach the beach.

D) Because waves go slower in shallower water, waves turn and move almost directly towards the beach, but the little bit of along-beach motion remaining drives longshore transport. Feedback: The rotation of the Earth has only miniscule effect at scales this small. Waves do go slower in shallower water, so as one end nears the coast, that end "waits" for the other end to catch up, causing waves to be going almost straight toward the shore when they run up the beach, but with just a little along-beach motion driving longshore drift.

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 space between the Sun and the Earth, but not through the soft, hot rocks of the mantle. 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, conduction always moves heat more efficiently than does convection. D) 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. E) No matter where you are, radiation always moves heat more efficiently than does convection.

D) 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. Feedback: 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.

The New Madrid Fault Zone in Missouri has had some surprisingly big earthquakes. A magneto-hydro-astronomer 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 covered so far in this 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) Listen up; although the forecast is not certain, such forecasts are usually fairly accurate and should be heeded. 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) 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. E) Invest in soda stocks; people always want cold caffeinated drinks after an earthquake, and an earthquake is highly likely at the time and place predicted.

D) 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. Feedback: 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. Planetary-alignment 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.

Silica released by chemical weathering is transported by streams to the ocean, where much of it: A) Reacts with hot sea-floor rocks to make different minerals there B) Is subducted back into the mantle at the mid-ocean ridges C) Is extracted from the water by marine dairy cows to add to milk D) Is used by sea creatures to make their shells E) Builds up in the water, making the ocean saltier

D) Is used by sea creatures to make their shells Feedback: Diatoms, radiolarians, and some sponges are among the creatures that make silica shells, from the silica provided by weathering of rocks on land. Silicate ions do not evaporate easily, and are not very common in the atmosphere. A little bit of sea salt, and anything else small in the sea, does escape in spray (stand by the sea on a windy day and you'll get sponts on your sunglasses), but most of the silica reaching the sea is used there. The "saltiness" of the ocean is a quite different chemical, not silica. Some shells are subducted, many more are scraped off downgoing slabs at subduction zones, but subduction does not occur at mid-ocean ridges, which is where sea floor is made, not where sea floor is consumed. Silica is not a major ingredient of milk, although a little silica in some grasses can cause a lot of tooth wear.

A grand piano in a house in one of the lowest-elevation regions of New Orleans protected by the human-made levees is: A) The same elevation as a kayaker in the river during a flood. B) Guaranteed to be purple, because only purple grand pianos are allowed in New Orleans. C) Lower in elevation than a kayaker on the river during a flood, but higher than the kayaker when the river is carrying its average water flow. D) Lower in elevation than a kayaker on the river when the river is carrying its average water flow. E) Higher in elevation than a kayaker on the river during a flood.

D) Lower in elevation than a kayaker on the river when the river is carrying its average water flow. feedback: In his book on the Mississippi, John McPhee noted that if you could take a supertanker out of the river, keep it at the same elevation but get it past the levees, it would hover over the floor of the Superdome like a blimp. The kayaker is the same; the low parts of the city are below river level even at low-water, and some of the city is below sea level as well.

The arrows point to an interesting feature, high in a road cut in the folded Appalachians of western Maryland.What happened here? A) Slide-past forces caused one side of the rock to slide past the other side. B) The sediments in the rock layer near the arrows were deposited this way; muds and sands normally form overlapping shingle-type patterns such as this. C) Pull-apart forces broke a rock layer, and earthquakes happened as one side slid past the other as they were pulled apart. D) Push-together forces broke a layer during folding and shoved one side over the other side. E) High-temperature metamorphism caused the rocks to soften and flow, with one side "dripping" under the other.

D) Push-together forces broke a layer during folding and shoved one side over the other side. Feedback: It is always shorter around the inside of a curve than around the outside, a fact well-known to NASCAR drivers and wannabees. The rocks above were folded in the great collision that made the Appalachians, which tends to stretch the rocks on the outside of the curve (near and below the bottom of the picture) and squeeze the rocks on the inside. If the rocks are brittle and don't "want" to flow, they may break, giving patterns such as that shown by the arrows. You can see similar things in many places; if you happen to visit Penn State's University Park campus, such features are exposed in the road cut along the Rt. 322 expressway just southeast of East College Avenue.

Extra polymerization of silica in some lavas makes them lumpier than typical. Ways to increase this polymerization of silica to make the lava even lumpier include: A) Adding iron. B) Adding iron, water and carbon dioxide, and heating more. C) Heating the lava more. D) Removing water and carbon dioxide from the lava. E) Adding water and carbon dioxide to the lava.

D) Removing water and carbon dioxide from the lava Feedback: 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.

Geologically speaking, the water table: A) Rises in elevation during times of drought as trees suck it up, and sinks during rainstorms as trees quit pulling up water because they are well-watered. B) Sits next to the coffee table in the Capitol Building. C) Never changes its elevation, because it is pinned by the creeks. D) Rises during or soon after rainstorms as spaces fill up, and sinks during droughts as water drains away. E) Changes elevation randomly.

D) Rises during or soon after rainstorms as spaces fill up, and sinks during droughts as water drains away. feedback: As trees suck up water during droughts, air enters spaces where water once was, so the water table (which is the bottom of the region with some air in spaces) must sink in elevation. Creeks do change in elevation between rain and drought (floods happen...), and while there are random elements in the world, this is surely not one of them. (Whenever someone claims something is random, at least suspect that the person is really saying "I don't know what I'm talking about, and I'm too lazy to find out.") And while there might be bottled water in the Capitol, geologically speaking, that is not the right answer.

In the photo above, Sam Ascah is standing on sand and gravel in a pothole, where a stream swirls during the short but intense thunderstorms of Zion National Park. And next to that stream, the other picture shows the sandstone and the hang-on-so-you-don't-fall-over-the-cliff chain along the trail. A likely interpretation of these features is: A) The Park Service carefully cut little grooves behind the chain before they hung it, so that it would look cute and slide well, and they cut the potholes so that hikers would have something to look at. B) The potholes and the grooves behind the chain were gnawed by giant marmots. C) The potholes and the grooves behind the chain were gnawed by giant beavers. D) The grooves behind the chain have been cut over decades by motion of the chain as hikers grabbed it, and the potholes were cut by water swirling rocks around during the rare floods over much longer times. E) The stream swirled rocks around and cut the potholes, and even bounced up the cliff to cut the notches behind the chain.

D) The grooves behind the chain have been cut over decades by motion of the chain as hikers grabbed it, and the potholes were cut by water swirling rocks around during the rare floods over much longer times. Feedback: The chain really has hung there for decades, and has been scraped against the cliff dozens of times per day each summer, slowly wearing into the easily broken sandstone. The stream does swirl rocks around and slowly wear down the potholes. The potholes were there beside the cliff when the trail was established, and havent changed too much over decades.

What type of mass movement moves the most material, averaged over the Earth's land and over long times? A) The landslides are lubricated by marmot number 2, while soil creep is greased by bird droppings, and marmot number 2 is more slippery so landslides go faster. B) The rare, large events move the most material. C) The many, small events and the few, large events move exactly the same amount of material. D) The many, small events move the most material.

D) The many, small events move the most material. Feedback: As rocks move to streams in many places, such as Pennsylvania, the slow and steady motions are more important than the few dramatic events. Specific places may be dominated by the few, dramatic events, especially in steep mountains, but across the Earth soil creep probably dominates.

High temperature and pressure tend to favor flow rather than breakage, so it is surprising that large, very deep earthquakes are sometimes observed, occurring in warm places where the pressure is high. What is accurate about these rare, deep earthquakes? A) They occur when volcanic bombs are set off by the rising heat of the Earth. B) They occur at hot spots, where the rising pressure on rock as it is buried by the growing volcano causes Pepsi machines to explode. C) They occur when nuclear bombs are set off by the rising political tensions on the Earth. D) They occur at subduction zones, where the rising pressure on rock as it is taken deeper seems to cause "implosion" of minerals as they rearrange to take up less space. E) They occur at spreading ridges, where the rising pressure on rock as it is brought up from below seems to cause "implosion" of minerals as they rearrange to take up less space.

D) They occur at subduction zones, where the rising pressure on rock as it is taken deeper seems to cause "implosion" of minerals as they rearrange to take up less space. Feedback: "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 one-on-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.

Large rivers sometimes have natural levees because: A) The mud deposited by the river compacts and sinks. B) Point bars run together to make levees. C) There are no natural levees. D) Water slows and deposits sediment as the water leaves the main river channel during floods. E) Oxbow lakes run together to make levees.

D) Water slows and deposits sediment as the water leaves the main river channel during floods. feedback: The initial slowdown as water spreads into the trees deposits sediment to form natural levees. Sinking mud doesn't make ridges. Point bars are the sand bars on the insides of meander curves, and oxbow lakes are abandoned meander curves, but neither makes the natural levees that are observed.

Dr. Alley is pointing to a brownish zone exposed in the low bluff along Coast Guard Beach, Cape Cod National Seashore. The brown zone is rounded on the bottom, flat on the top, rests on sand and gravel, and has sand dunes on top. In the lower picture, Dr. Alley is showing that the brown zone contains twigs and other organic material. What is the brown zone doing here? A) Humans dammed a nearby river, forming a lake that then filled with organic material. B) A sinkhole opened here, forming a lake that was then filled with organic material. C) The brown zone is mostly the carcass of a dead whale, which was propelled here when highway-department workers dynamited it to get it off the beach. D) The brown zone is mostly the carcass of a dead whale, which washed up on the beach and was buried. E) An ice block from the glacier was buried in sand and gravel, then melted to make a lake that filled with organic material.

E) An ice block from the glacier was buried in sand and gravel, then melted to make a lake that filled with organic material. Feedback: Cape Cod is a creature of the glaciers, and most of the Cape's lakes started by melting of buried ice blocks. Sinkholes and human-made lakes do fill with organic material sometimes, but this is the wrong setting. A whale carcass wouldn't be twigs, etc. In Oregon, the highway department did once try dynamiting a whale carcass to speed natural decay, and succeeded in splattering bystanders and even denting some car roofs with large flying whale parts. (One has to wonder whether there exists a rock band somewhere named "Large Flying Whale Parts".)

The sea floor that forms at spreading ridges and then moves away will: A) Be ground up by glaciers, blown away by wind, and eventually escape to space in the solar wind. 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) Remain at the surface of the earth forever, resulting in the earth getting bigger and bigger every year. D) Be bulldozed and used as construction material for new buildings in Washington. E) Be subducted, with most of the material going back into the mantle, balancing the material coming out to make the new sea floor.

E) Be subducted, with most of the material going back into the mantle, balancing the material coming out to make the new sea floor. Feedback: 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.

The recent changes in the amount of ice on Earth over time occurred: A) Because flocks of giant ptarmigan and herds of giant marmots clustered on the edges of the ice sheets, which melted the ice. B) Because changes in the Earth's orbit have caused large changes in the total amount of sunshine received by the Earth. C) Because the Earth has swung through giant clouds of dust in space that blocked the sun and caused global cooling. D) Because of the actions of a Serbian mathematician, Milutin Milankovitch. E) Because changes in the Earth's orbit have caused changes in the amount of sunshine received during certain seasons at different places on Earth.

E) Because changes in the Earth's orbit have caused changes in the amount of sunshine received during certain seasons at different places on Earth. feedback: Milankovitch studied the effect of orbital features on received sunshine, and hypothesized that this may have caused ice ages, but he surely didn't cause the ice ages, which happened long before he was born. The orbital changes have little effect on the total sunshine, but do move that sunshine around, with important consequences. The giant-dust-cloud hypothesis was entertained seriously by scientists for a while but doesn't work; however, like essentially all serious hypotheses that fail, this one is alive and well in the fringe-science web sites of the internet. I'd love to have seen flocks of ptarmigan and herds of marmots, but no one has found their bones, so it is highly likely that they did not exist.

You are flying along the coast, and you observe a sort of dam or wall, called a groin, sticking out from the coast. Sediment has piled up on one side of the groin, with erosion on the other side. You can reasonably infer that: A) Before the groin was built, the beach was building out rapidly, so the landowners built the groin to make their beach smaller. B) Before the groin was built, sediment transport in the longshore drift was dominantly from the side with the erosion to the side with the sediment deposit, and the groin has made this transport much faster. C) The groin of the beach is attached to the pelvis of the beach at the elbow of Cape Cod, making for some strange scientific anatomy. D) Before the groin was built, the beach was perfectly stable, so the landowners built the groin primarily to cause a longshore drift to begin so that the beach would move. E) Before the groin was built, sediment transport in the longshore drift was dominantly from the side with the sediment deposit to the side with the erosion, and the groin has interrupted some of this transport.

E) Before the groin was built, sediment transport in the longshore drift was dominantly from the side with the sediment deposit to the side with the erosion, and the groin has interrupted some of this transport.

Tsunamis: A) Can be predicted accurately months in advance, allowing evacuations. B) Invariably involve water moving away from the coast before extra water comes in. C) Always are huge and destructive. D) Are completely unpredictable, so there is nothing we can do about them. E) Can be predicted with some accuracy seconds to hours before the waves strike in most cases, allowing quick warnings to save many lives.

E) Can be predicted with some accuracy seconds to hours before the waves strike in most cases, allowing quick warnings to save many lives. Feedback: Because tsunamis are triggered by earthquakes, among other things, and we cannot predict earthquakes accurately, we cannot make months-in-advance predictions of tsunamis. The p-waves from the earthquakes that cause the most common tsunamis move more rapidly than the tsunamis do, allowing timely warnings; however, because the tsunamis get where they are going in hours or less typically, not much time is available. Water does go out before rushing in along some coasts, but comes in before going out along other coasts, waves have "up" and "down" parts, and some coasts get an "up" first while other coasts get a "down" first. Little earthquakes make little tsunamis; big earthquakes make big tsunamis.

You watched online as Dr. Alley carved a sand canyon with his finger. Based on what you saw, and on what you know about slopes, stability, mass movement, etc., if a landslide happened someplace last week, you would tell the neighbors: A) All is safe now; nature relieves stress and removes instabilities, and that is what the landslide did. B) Run for your lives! Landslides are always followed by floods and more landslides. C) Special care is required; landslides invariably trigger earthquakes. D) Run for your video cameras! Landslides are invariably followed by professors sticking out fingers, and you can get footage to win megabucks on America's Funniest Classroom Videos. E) Care is required; landslides are removing instabilities and moving things towards stability, but a second landslide, or a flood, or other problems are real possibilities.

E) Care is required; landslides are removing instabilities and moving things towards stability, but a second landslide, or a flood, or other problems are real possibilities. Feedback: When Dr. Alley made a "landslide", others often followed, but not always. Similar behavior is often observed in nature. The Gros Ventre slide near the Tetons dammed a river, with dam failure later releasing a flood, but a flood was avoided at Hebgen Lake outside of Yellowstone. And so far, we don't think that America's Funniest Classroom Videos is handing out megabucks. But let us know if they start.

If you went swimming in the single channel of this river, and grabbed a sample of the river bank, what would you likely come up with? A) A mixture of clay, sand and boulders, called till. B) Sand, that can make really steep slopes such as are seen in sand castles. C) Sand, that collapses to plug channels . D) Boulders, that pile together to hold up river banks. E) Clay, that sticks together and can hold up steep slopes.

E) Clay, that sticks together and can hold up steep slopes. feedback: This is a meandering channel, and these normally are fairly deep and narrow, so the materials of the banks should be able to stick together and support a steep slope. Sand can be steep when damp, but slumps to nearly flat when wet, and boulders or too much sand plug streams and make a braided pattern, whereas clay can make very steep slopes.

Given the materials presented in this class about the formation of caves, it is likely that most large caves are formed: A) In sandstone in moist climates. B) In limestone in dry climates. C) In sandstone in dry climates. D) In granites under Diet Pepsi. E) In limestone in moist climates.

E) In limestone in moist climates. feedback: Caves require easily dissolved rock, and water to dissolve that rock. In really dry climates, limestone is a resistant rock that stands in huge cliffs. In wet climates, limestone dissolves to yield caves. Sandstone is not a good cave-former because sandstone does not dissolve easily. (Yes, there are very shallow rock-shelter caves in sandstone, which is why the question specifically notes "large caves".) And while Diet Pepsi actually would be marvelous at dissolving limestone, Diet Pepsi attacks granite rather slowly and won't make caves well.

Mt. St. Helens, in the state of Washington: A) Is a low-silica basaltic volcano, different from the andesitic volcanoes of Hawaii. B) Is a broad, flat shield volcano, different from the steep stratovolcanoes that are seen above sea level in Hawaii. C) Is a broad, flat flood basalt, different from the steep stratovolcanoes of Hawaii. D) Has only experienced one eruption, on May 1, 1980, in the same way that a Hawaiian volcano experiences only a single eruption. E) Is a medium-to-high-silica andesitic volcano, different from the lower-silica basaltic volcanoes of Hawaii.

E) Is a medium-to-high-silica andesitic volcano, different from the lower-silica basaltic volcanoes of Hawaii. Feedback: 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 like the above-sea-level parts of the basaltic (lower-silica) Hawaiian volcanoes. 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, just as Hawaiian volcanoes have numerous eruptions.

Dr. Alley has helped drill many holes in ice sheets. Special tools can be lowered down the holes on cables, and tracked to learn the shapes of the holes. Initially, the holes are straight up and down. Years later, the holes are bent, because the ice in the ice sheet is flowing. What does it mean to say that the ice is flowing? A) The drill used to make the hole has melted the whole ice sheet, the water flowed for a while, and then refroze when the drilling stopped. B) The ice is enjoying the summer, relaxing, hanging out with its friends, just, you know, going with the flow. C) The drill used to make the hole has shaken the ice so that it broke into chunks, which rolled downhill. D) The ice is so far below its melting point that it is dense enough to sink into the rocks beneath it, bending the hole as it does so. E) Much like rocks in the mantle or iron heated by a blacksmith, the ice is almost hot enough to melt, and deforms as gravity pulls on it, without breaking into loose chunks.

E) Much like rocks in the mantle or iron heated by a blacksmith, the ice is almost hot enough to melt, and deforms as gravity pulls on it, without breaking into loose chunks. feedback: Materials warmed almost but not quite to their melting point can deform without breaking or melting. We saw this with the great convection cells in the mantle, back in unit 2, and we meet it again with ice. If you list the temperature of the ice in degrees F, it is a lot colder than the mantle, or iron heated by a blacksmith, or a chocolate bar in your pocket. But, the ice has been warmed from absolute zero almost to the melting temperature, just like the mantle and the iron and the chocolate, so the stress from gravity can cause the ice to deform or flow.

If two drifting continents run into each other: A) Both will be subducted back into the deep mantle, forming a new subduction zone. B) The older, colder one will sink into a giant subterranean lake of Pepsi One. C) The older, colder one will sink into the core. D) The older, colder one will be subducted back into the deep mantle, forming a new subduction zone. E) Neither will be subducted back into the deep mantle; instead, they will form an obduction zone.

E) Neither will be subducted back into the deep mantle; instead, they will form an obduction zone. Feedback: "The Unsinkable North America" might not make it as a vehicle for show tunes, but continents have floated around for 4 billion years and are unlikely to sink in the near future. Old, cold sea floor can sink into the mantle, but continents are lower in density than sea floor and cannot follow. A continent could sink into a subterranean lake of Pepsi One if such a thing existed, but no such thing exists.

Pictures I and II show famous volcanoes. What is accurate about these? A)Picture I shows a hot-spot-type cinder cone, and picture II shows a subduction-zone-type shield volcano. B) Picture I shows a hot-spot-type shield volcano, and picture II shows a subduction-zone-type stratovolcano. C) Picture I shows a hot-spot-type shield volcano, and picture II shows a pile dug up by a big marmot named George. D) Picture I shows a subduction-zone-type cinder cone, and picture II shows a head-of-hot-spot-type shield volcano. E) Picture I shows a subduction-zone-type stratovolcano, and picture II shows a hot-spot-type shield volcano

E) Picture I shows a subduction-zone-type stratovolcano, and picture II shows a hot-spot-type shield volcano Feedback: 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.

The picture above is of the coast at Acadia National Park. Look at the shape of the rocky island marked with the big "I" in the middle of the picture. The most likely interpretation is that this was caused primarily by: A) Sculpting of the rocks by wind, followed by flooding as sea level rose at the end of the ice age. B) Sculpting of the rocks by a glacier, which flowed from the right to the left. C) Sculpting of the rocks by stone masons hired by the Rockefellers, followed by donation of the sculpture to the people of Maine. D) Sculpting of the rocks by waves, followed by uplift of the rocks above sea level as the land rebounded from the weight of the ice sheets. E) Sculpting of the rocks by a glacier, which flowed from the left to the right.

E) Sculpting of the rocks by a glacier, which flowed from the left to the right. Feedback:The side of the rock that a glacier reaches first is sandpapered and rounded blocks are removed. The ice thus flowed from left to right, streamlining and smoothing the island. Wind and waves do not make such distinctive forms, and while Rockefeller stonemasons might have done so, they probably would have carved a huge likeness of a fabled ancestor instead.

What tectonic setting is primarily responsible for producing the great San Francisco earthquake and the San Andreas Fault? A) Push-together Obduction B) Push-together Subduction C) Hot Spot D) Pull-Apart E) Slide Past

E) Slide Past Feedback: Not much mountain-building is happening along the central coast of California; the rocks slide past horizontally. The sliver of California to the west of a line connecting San Francisco to Los Angeles is sliding to the northwest, and as the sliver slides, it sticks and slips, making earthquakes.

The map above shows the Birdfoot Delta of the Mississippi River, where it empties into the Gulf of Mexico. The river is shown in blue, as is the Gulf of Mexico. The river "wants" to leave this delta, and flow somewhere else, far to the west of the area covered by this map. Why? A) As the mud of the delta sinks, the river loses its river banks, so it flows elsewhere. B) The meandering of the river has tied it in a knot, so it has to take a different path. C) Hurricane Katrina, in 2005, plugged many of the river channels, so the river must go elsewhere. D) Humans have been damming the river at the end, so the river must go elsewhere. E) The delta has built up as well as out, and that makes some other path to the Gulf steeper and shorter than the one now being taken, and during a flood the river tends to take that shorter path and cut a new channel.

E) The delta has built up as well as out, and that makes some other path to the Gulf steeper and shorter than the one now being taken, and during a flood the river tends to take that shorter path and cut a new channel. feedback: The river very nearly broke through the Old River control structure in a big flood, to take the shortcut down the Atchafalaya. The long path out to the end of the delta is not very favorable for the river, which has switched naturally in the past and would switch if humans allowed it to.

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 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. C) 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. D) 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. E) The downgoing slab takes water and other things along, which lower the melting point down there enough to make melt that feeds the volcanoes.

E) The downgoing slab takes water and other things along, which lower the melting point down there enough to make melt that feeds the volcanoes. Feedback: 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.

Air that passes over the Sierra Nevada from the Redwoods to Death Valley is warmed by roughly 30oF, even if the air goes over at night. Where does the energy come from? A) Sunshine heating the air while it is passing over the mountains B) Volcanic eruptions from the peaks along the Sierra C) The rotation of the Earth, which causes winds to curve as they blow over the surface D)Gas-passing marmots, such as George, seen below; E) The heat that had been stored during evaporation from the ocean and was released when clouds formed on the west side of the Sierra

E) The heat that had been stored during evaporation from the ocean and was released when clouds formed on the west side of the Sierra Feedback: Much of the sun's energy that falls on the tropics is stored by evaporating water, and only later made so you can feel it (called sensible heat) when condensation reverses the evaporation. If the warming happens at night, then direct warming from the sun cannot be correct. The Sierra is no longer volcanically active, and volcanoes rarely emit enough heat in a broad enough zone to affect general winds much. The Earth does rotate, and this does cause winds to curve as they blow over the surface, but that curving doesn't add heat to the system. And while marmots do produce a little methane, and a bit of heat, they don't produce nearly enough to matter to the climate.

Shown above is Great Rock, Cape Cod National Seashore, with some of Dr. Alley's relatives for scale. The rock is metamorphic. The picture includes most but not all of the above-ground portion; the rock goes about as far below ground as above. What is the rock doing here in the middle of Cape Cod? A) The rock was thrown here by the giant meteorite impact that hollowed out Hudson Bay. B) Tsunami waves washed it here, when a huge landslide occurred from a volcanic island in the Atlantic Ocean. C) The rock rose up through the sand during a giant earthquake, the way large rocks are "floated" up in permafrost regions. D) The rock was used as ballast on the Mayflower, and left at First Encounter Beach as a present to the native Americans because the Mayflower no longer needed ballast in thenear-coastal waters. E) The rock was carried here by glacier ice and left when the ice melted.

E) The rock was carried here by glacier ice and left when the ice melted. Feedback: Glaciers carry rocks of all sizes easily. Cape Cod is the product of glaciers, and almost everything natural on the Cape was delivered by glaciers originally. There rarely are big tsunamis in the Atlantic, but not this big. Nor is there any evidence of a big meteorite impact that is as young as Cape Cod. The east coast is rather free of large earthquakes, although Charleston, South Carolina gets a few occasionally. And the early settlers would not have put such a huge thing in the bottom of their ship (imagine having that bouncing around in a storm!), nor could they have taken such a rock out easily upon arrival.

You are hiking in the mountains and find some snow and ice. You drill a hole in the snow and ice to the bottom but not into the materials beneath. Later, you come back and meausure the shape of the hole, and find that there has been no change. Based on the definition of a glacier, you should conclude: A) You cannot tell whether the snow and ice is a glacier, because you did not measure whether there is any Pepsi beneath, and all glaciers slide on Pepsi. B) The snow and ice you found must be called a glacier, because all snow and ice are in glaciers. C) The snow and ice you found are a glacier, because glaciers do not have deformation. D) You cannot tell whether the snow and ice is a glacier, because you did not measure whether there is any sliding of the ice over materials beneath. E) The snow and ice you found are not a glacier, because glaciers must have deformation in the ice

E) The snow and ice you found are not a glacier, because glaciers must have deformation in the ice Feedback: Deformation within the ice is the hallmark of a glacier. Other motion may or may not occur.

The floor of Death Valley is about two miles lower than the mountain peaks around it. How did this happen? A) The valley floor has dropped by exactly two miles relative to the mountains. B) The valley was once filled with a giant lake of coffee, and early miners collected the coffee and hoarded it so they could sell it to Congress under an exclusive licensing agreement. C) The elevation difference between the peaks and valley was once much larger than two miles, but the valley floor has been rising as it is inflated by lava from below. D) The valley was carved two miles deep by a prehistoric river, much in the same way that the Colorado River carved the Grand Canyon. E) The valley floor has dropped by more than two miles relative to the mountains, but erosion has removed the mountain tops and the sediment produced has partially filled the valley, leaving an elevation difference of two miles.

E) The valley floor has dropped by more than two miles relative to the mountains, but erosion has removed the mountain tops and the sediment produced has partially filled the valley, leaving an elevation difference of two miles. Feedback: Watch a stream flowing into Death Valley (or any other valley) during a thunderstorm, and you will see that the water is full of rocks, mud, etc. The mountains are being eroded, and the loose pieces are carried down and dumped into the valley. Yet the mountain peaks are still two miles above the floor of Death Valley; the erosion and deposition are fighting against faulting that has dropped the valley by more than two miles relative to the mountains. No river carved the valley; the rivers are filling it up. And strange as it may seem, the valley is older than Congress or brewed coffee.