Rock On Quizzes

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The gas from the Marcellus shale:

Is produced by "fracking", which uses high-pressure water and chemicals to make new "fractures" in the shale that allow the gas to escape to wells. Water containing special chemicals is pressurized in holes bored through the Marcellus Shale, breaking the rocks to make pathways that allow the gas in the rock to escape through the holes to the surface, where it can be sold.

Calcium released by chemical weathering is transported by streams to the ocean, where much of it:

Is used by clams, corals, etc. to make their shells. Most common shells seen at the beach are calcium carbonate, and the calcium is provided by weathering of rocks on land. Calcium 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 spots on your sunglasses), but most of the calcium reaching the sea is used there. The "saltiness" of the ocean is a quite different chemical, not calcium. 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. Calcium in milk is a good thing, and helps build strong bones and teeth, but dairy cows rarely go to the beach to go swimming, and wouldn't enjoy drinking the water to get their calcium. There is a little bit of calcium in grasses, and cows get some of their calcium from there

What is accurate about the scientific theory of evolution today?

It is being applied successfully in the real world in many ways, including helping fight new disease organisms, and even guiding the thinking of computer scientists.

Pictures 1 and 2 show two very different looking rivers. What can you say about them?

1 is a meandering stream with clay-rich banks, and 2 is a braided stream with sandy or gravelly banks.

You start with 800 parent atoms of a particular radioactive type, which decays to give stable offspring. You wait just long enough for two half lives to pass. You should expect to have how many parent atoms remaining (on average):

200. After one half-life, you've gone from 800 parents to 400 parents; after a second half-life you go from 400 parents to 200. . (Typical studies of radioactive decay use many more atoms, to avoid statistical fluctuations, but the question says "on average", so we asked you about 800 rather than 800,000,000,000,000 to make the math easier.)

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.)

3 feet. 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.

The extinction of many types of dinosaurs occurred about:

65,000,000 years ago. Humans were trotting around 65,000 years ago, and met dinosaurs only in The Flintstones. 650,000 years is barely enough time for evolution to have changed large animals a bit, and although 6,500,000 years is enough time for noticeable change of large animals—increase in maximum size of members of the horse family, for example—the huge changes since the dinosaurs needed 65,000,000 years. 650,000,000 years goes back before any land creatures, and before all but the simplest of multi-celled organisms.

This rock in the picture above was modified by:

A glacier, which scratched and polished the rock at A and plucked blocks loose at B, as the ice moved from A to B. 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.

The picture above shows:

A right-side-up dinosaur track. This is a dinosaur track, from dinosaur ridge, and the dinosaur stomped down into the mud, so the track is right-side-up.

Which is accurate about the Grand Canyon, in Arizona:

A great thickness of sedimentary rocks exists in Death-Valley-type faulted basins, which can be seen deep in the canyon in many places. Well over two miles of Precambrian sedimentary rocks can be seen in the deep part of the canyon, all slanted from horizontal and preserved where they were dropped by faulting. The sedimentary rocks above are right-side up, and the Coconino Sandstone is well below the Kaibab Limestone of the rim, which slants down to the north beneath the rocks of Zion, which are older than the rocks of Bryce, among others. Many unconformities exist in the walls of the Canyon, including the one below the Precambrian sediments and the one above those sediments. The idea of the river narrowing over time was the hypothesis that an interested tourist presented to one of the professors and a ranger at the Canyon a few years ago. When the professor asked whether the tourist would want to go out on a narrow point with a jackhammer, the tourist said no, because the rocks might fall off and slide down into the Canyon. When the professor pointed out the many places that rocks had fallen off and slid down, the quick-witted tourist figured out that the Canyon has been widened by such rockfalls as the river has cut downward.

Look at the picture above. What happened here?

A great volcanic explosion occurred, spreading material across the landscape and leaving a hole.

What can you learn about past environments from sediments and sedimentary rocks?

A huge amount, including whether the environment was land or water, whether it was warm enough for crocodiles or cold enough for ice, and much more.Feedback:From the size, shape and arrangement of grains, the type or rock, the fossils, and more, a great amount can be learned about the environment that existed when the sediment was deposited.

When scientists agree that a particular scientific theory is a good one, and the scientists use that theory to help make new things, cure diseases, etc., that "agreement" came about because:

A number of different experiments by different people all had outcomes that were well-predicted by the theory. Agreement on scientific theories is a contentious, drawn-out, and sometimes acrimonious business. Scientists are no better (and no worse!) than everybody else: we think we are right and those who disagree with us are dunderheads! I put forward my idea, and the experiments that I did that show the idea is a good one... then everybody else piles on and pooh-poohs my idea. BUT, they go out and do experiments that try and show my ideas are wrong... and they can't do it! So eventually all those experiments accumulate, and finally people agree that my idea is a good one. (Sometimes accompanied by a sneer: "...but of course I knew that all along. I just didn't bother to publicize it..." I told you, scientists are no better and no worse than the rest of the world.)

You see a hot-spot volcano on the surface of the Earth. What is under this volcano?

A rising tower of hot rock from deeper in the mantle, and perhaps all the way from the bottom of the mantle(Earthquakes make sound waves that go through the whole Earth, and go slower through hotter, less-dense rocks. By setting out listening devices called seismometers around the Earth, and listening to the waves from many earthquakes in many places, scientists can map the hotter regions, and find that towers of hot rock come up from way deep in the Earth in some places. But, some other hot spots, while clearly coming up from below, don't seem to start quite as deep.)

Volcanoes of many different types can be observed at the surface of the Earth. Suppose you are looking at a hot-spot volcano. If you could see deep beneath that volcano, what would you find?

A rising tower of hot rock, coming up from below and perhaps from waaaaay below, down at the bottom of the mantle.

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 river-built deposit that is several miles thick at its thickest point, and extends from near St. Louis, Missouri to the Gulf of Mexico. 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!

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 storm broke through the barrier beach and pushed sand farther inland. 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.

An unconformity is:

A time gap in a sequence of sedimentary rocks caused by a period of erosion or nondeposition.

Look at the picture above which shows a region just less than a foot across, of a stream deposit from the base of the same pile of rocks that show up in Bryce Canyon. This picture was taken in the face of a cliff in Red Canyon, just west of Bryce Canyon National Park.A indicates a piece of limestone that has been rounded off in a stream; B indicates a mass of sand glued together by hard-water deposits, and C indicates another such mass of sand glued together by hard-water deposits.In order of time of formation, they are:

A was formed first, then B was glued together by hard-water deposits, then C was glued together by hard-water deposits.

There are many greenhouse gases, including carbon dioxide (CO ), methane (CH ). and vaporized water (H O). These and other greenhouse gases warm the Earth primarily by:

Absorbing some of the infrared radiation emitted from the Earth. Although it is true that squeezing air warms it, the pressure does not set the temperature (change in pressure brings change in temperature), and, the greenhouse gases are really very rare and don't affect pressure much. Clouds are not caused by greenhouse gases, and while clouds warm nights, clouds cool days, and the net effect of clouds is probably slight cooling of the planet. Convection currents are blocked by the glass of greenhouses, but not by greenhouse gases. But CO does absorb some of the infrared radiation emitted from the planet. Absorbing an infrared photon puts a CO molecule into an excited state, and fairly quickly the molecule returns to its unexcited state by emitting a photon of the same energy. Some of those photons emitted by excited CO molecules head back toward Earth (the emission direction is random). So, the CO serves to trap energy in the Earth system, warming the planet so that it glows more brightly to shove infrared radiation past the CO , achieving a new balance.

Air moves in from the Pacific, over the Sierra Nevada (a mountain range), and down towards Death Valley. What happens?

Air moving down the east slope toward Death Valley is compressed, and warms by about 5 degrees F per thousand feet downward. As the air moves down, it is compressed and warms, by about 5 degrees F per thousand feet downward

What is accurate about the planet's climate system?

Almost the same amount of energy is received from the sun as is sent back to space, but shortwave radiation is received and longwave radiation is sent back to space. Energy in equals energy out, to very close approximation. We actually send back the tiniest bit more, because the Earth makes a little energy radioactively and because we are mining stored energy (fossil fuels) and burning it, and some of that goes to heat the atmosphere but some is lost to space. But, these differences are tiny tiny tiny. (Lie in the sun on the grass on a hot day, and see if you can tell whether the sun or the Earth is supplying the most heat to your skin...). We receive shortwave—visible light—and send back longwave—infrared.

Suppose that tomorrow someone bulldozed all the rocks in the Appalachians, right down to sea level, and shipped all of those bulldozed rocks to Uzbekistan to build ski slopes. A few thousand years from now, we probably would find that the surface of the Earth exposed by the bulldozers was:

Almost, but not quite, as high as the Appalachians are today, because the roots of the mountains bobbed up. Nine-tenths of an iceberg, or an ice cube, is below water, with onetenth above. The iceberg is big, the ice cube little, and one-tenth of big is more than one-tenth of little, so the iceberg sticks up higher than the ice cube. Cut the top off the iceberg, let it bob up, cut the top off, let it bob up, and you're slowly turning the berg into a cube, so each time the height of the berg is reduced a little. Same is true for a mountain range—cut the top off by erosion, bobs up almost as high as before, erode the top off, repeat, and slowly the height is reduced. The initial thickness was made by the collision of obduction, but then erosion and bobbing-up take over.

If North America and Asia continue drifting towards each other across the Pacific at their modern rates, they must someday develop what?

An Appalachian-type or push-together obduction boundary. Obduction happens when two continents are pushed together in a collision. If North America and Asia continue to drift together, eventually the continents will collide, forming an obduction zone.

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:

An arête, left between the bowls formed by two glaciers that gnawed into the mountain from either side. 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???

Chemists recognize many different elements, such as gold, or oxygen, or carbon, or iron. Suppose you got some iron, and started splitting it into smaller pieces. The smallest piece that would still be called "iron" would be:

An atom We can break matter down into atoms (Greek for "not cuttable" because the Greeks didn't have atom smashers or other exotic tools that would allow cutting atoms into smaller pieces). All of the wrong answers here are smaller pieces of atoms, but they wouldn't be gold any more; you can make any of the elements out of these pieces.

Which of the following is commonly expected near a "textbook" subduction zone (that is, near a subduction zone that is so perfect and free of confusing complications that you would use it in a textbook to teach students)?

Andesitic stratovolcanoes, such as Mt. St. Helens.

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?

An ice block from the glacier was buried in sand and gravel, then melted to make a lake that filled with organic material. 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".)

A widely accepted scientific idea usually is based on:

An interlocking web of important experimental results or observations that support the correctness of the idea. At last observation, Pepsi commercials were not highly scientific, even if science is involved in figuring out what sells. It is a romantic notion that you could overturn great knowledge with a single observation; however, observing nature is not easy, and nature occasionally fools us (you can, rarely, flip an honest coin twenty times and get twenty heads), so if a single observation disagrees with a lot of other information, that single observation will be checked in various ways to see if the new result "stands up" before the older body of knowledge is discarded. Before an idea gains wide currency, that idea is tried in various ways, in many labs, in many places in nature, while models are run and theory is developed. The interlocking of all of these provides the confidence that scientists can use in doing things successfully. Although received wisdom from sacred books can be used for inspiration, scientific ideas must be tested against nature. Social scientists have quite rightly learned that scientists are affected by their prejudices, their funding sources, their mating habits, and other things, and that the path of science is not nearly the straight-ahead road to understanding presented in some textbooks. Unfortunately, some of those social scientists have then gone off the deep end and claimed that science is no more useful than any other human story—claiming that astrology and astronomy are equally valid, for example, or palm-reading and modern medicine. These same social scientists seem to know where to find a real doctor when they get in trouble, however. Science is appealed to nature, and builds on the learning of people from around the world. Airplanes that fly, computers that calculate, small devices that make big explosions, etc. are not socially conditioned ideas but instead are demonstrations of the success of science coupled to engineering.

National Parks are:

An invention of the United States that has spread around much of the world, as a way of protecting some of the finest parts of the world. Yellowstone was the first National Park, but now you can find National Parks scattered across the planet, preserving key areas for the enjoyment of this generation and for future generations.

The age of the Earth can be estimated in many ways. Which statement below is most accurate (remember that uniformitarian calculations involve looking at the thickness and type of sedimentary rocks, and similar things, but do NOT include radiometric dating or counting of annual layers)?

Annual-layer counting shows that the Earth is more than about 100 thousand years old, uniformitarian calculations show that the Earth is more than about 100 million years old, and radiometric techniques tell us how old the Earth is.

Tsunamis:

Are caused by earthquakes, undersea volcanic eruptions, or anything else that displaces a lot of water in a hurry. 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".

When geologists consider sedimentary rocks, those rocks:

Are classified first based on origin (clastic or chemical precipitate). We do divide the rocks based on origin first. We saw with weathering that physical weathering makes chunks or clasts, and then chemical weathering also makes chunks (clay, rust, sand grains) and dissolved things. The clasts give clastic rocks, and when the dissolved things come out of solution, chemical precipitates are formed. Color is not often a useful indicator—rock colors change a lot during weathering, and colors also may change when oil or water move through. Grain size matters to clastics, but not much to precipitates.

Transitional forms between distinct types (species) of different ages in the fossil record:

Are common for commonly fossilized types, but rare for rarely fossilized types.

Weathering attacks a granite in Pennsylvania or Washington, DC, or a similarly rainy place. The quartz grains in the granite primarily:

Are loosened from the rock but don't change much, staying in the soil as quartz sand. Quartz dissolves just a bit, freeing silica that washes to the ocean to be used in shells. But most of the quartz hangs around in the soil as quartz sand.

What geological processes have caused the Grand Canyon to be wider at the top than at the bottom?

As the river cuts down, the steep walls of the canyon experience mass movement (rocks fall, slump, creep or otherwise move off the walls and down to the river), so the top of the canyon is widening as the river deepens the bottom. 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 upand-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.

The recent changes in the amount of ice on Earth over time occurred:

At regular and repeating times, controlled by redistribution of sunlight on the surface of the Earth in response to features of Earth's orbit, even though total sunshine received by the planet didn't change much. The orbital changes have little effect on the total sunshine, but do move that sunshine around, with important consequences. And the orbital changes are far from random, having very strong regularities. We'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.

In a glacier, the ice moves fastest:

At the upper surface, where ice meets air. The ice at the surface rides along on that beneath but deforms a bit on its own, and so goes fastest. The fast-food ketchup-packet model in which the mid-depth ice goes fastest would require that the upper and lower pieces be especially strong and rigid (which they aren't; and, it might require someone huge stomping on the glacier). The bed is held back by friction with the rock. And ice lacks the sentience needed to attempt to avoid commercials.

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?

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

Look at the picture above, which shows a small section of a "fossil" sand dune (a sand dune in which the grains have been "glued" together by hard-water deposits). When the dune was first deposited, which was up (which letter is closest to the arrow that is pointing in the direction you would have looked to see the sky when the dune was deposited)?

B. Just to the left of the letter ï¿½Bï¿½ there is a small unconformity. The layers farther to the left are cut along that surface. Layers must exist to be cut, so the left-hand layers are older, the right-hand layers are younger, and ï¿½upï¿½ was to the right.

Early scientists studying a glacier put stones on the ice surface in a straight line across the valley, and came back later to find that the line was bent and moved downhill. The scientists determined that the stones did not slide off the glacier, but were carried by the flow of the glacier. What did the scientists mean by "flow of the glacier"?

Because the ice was almost warm enough to melt, the ice deformed slowly something like hot iron in a blacksmith shop or a chocolate bar in your pocket. 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.

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?

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. 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.

If you were looking for different types of coal, you likely would find:

Bituminous in the sedimentary rocks of western Pennsylvania, and anthracite in the metamorphic rocks of eastern Pennsylvania. Bituminous is found with sedimentary rocks, but ones that have been squeezed and heated a bit so they are far from being loose sediment; such rocks are common in western Pennsylvania. Anthracite is the most-cooked coal, and is found with metamorphic rocks in eastern Pennsylvania. Pennsylvania has lots of coal, but not much lignite, which would not be found in metamorphic rocks anyway.

Both of the above pictures are along the Colorado River. The clear water of picture 1 and the muddy water of picture 2 appear quite different. What's going on?

Both of the above pictures are along the Colorado River. The clear water of picture 1 and the muddy water of picture 2 appear quite different. What's going on? The naturally muddy river is seen clearly in Canyonlands in 2. The river dumps its sedimentary load in the reservoir above the dam, so downstream of the dam the water is clear, as shown in 1.

Some natural resources are renewable—nature produces them fast enough that humans can obtain valuable and useful supplies of a resource without depleting it. Other natural resources are nonrenewable— if we use the resource at a rate fast enough to matter to our economy, the resource will run out because use is much faster than natural production. What do we know about oil and coal?

Both oil and coal are nonrenewable resources, and at current usage rates and prices similar to today, oil will run out in about a century and coal will run out in a few centuries. There is lots more coal than oil; oil has this habit of floating on water, thus rising through rocks and escaping to the sea floor where the oil is "burned" for energy by bacteria or other creatures. The size of the resource, in coal, oil, or anything else, depends on the price, and how long the resource lasts depends on rate of use, which is increasing rapidly for fossil fuels. The idea that immense pools of oil are out there, undiscovered but easy to get, is pretty silly—oil companies are really smart, drilled the easy stuff early on, and are now running out of oil that can be drilled and produced at prices close to modern.

You are the chief biodiversity officer for the National Park Service in the eastern US, responsible for maintaining as much diversity as possible, and your boss has told you to focus on maintaining biodiversity of things big enough to see with the naked eye (so you don't need to worry about microorganisms). You have two parks, and enough money to buy 10,000 acres of land. You may add the 10,000 acres to one of the parks, add 5,000 acres to each park while leaving them as isolated parks, or buy a 10,000-acre corridor connecting the two parks. All of the land for sale is now wilderness, but the land you do not buy is going to be paved for a super-mega-mall. You would be wise to:

Buy the corridor connecting the two parks; this keeps one big "island" rather than two smaller ones, and so keeps more species. Remember the terrarium—you will have more diversity in an undivided terrarium than in a divided one. Your park area is your terrarium; keep it undivided. Malls have low biodiversity.

The diagram above shows a geologic cross-section of some rocks, such as you might see in a cliff. The tree is growing on top of the modern surface. Rock layers A, B, C, D, E, and F are sedimentary; E contains mud cracks and fossil footprints as shown. G is igneous rock that hardened from hot, melted rock. H, I and J are faults, and K and L are unconformities. Sedimentary rocks are right-side-up unless there is some indication given to show something else. Referring to the rocks you see here ......Which is the oldest sedimentary rock layer?

C. The package of sediments C, D, E, and F is upside-down, as shown by the footprints and mud cracks, so C is the oldest one.

Which formula describes the chemical changes that occur and release energy when you start with plant material and then burn it in a fire or "burn" it in a stomach?

CH2O + O2 → CO2 + H2O. CaCO3 is shell or cave-rock; the equation with CaCO3 on the left is dissolution of rock to make caves, and the equation with CaCO3 on the right is formation of shells. CH2O is a pretty good estimate of average plant composition; the equation with CH2O on the left is burning of plant material for energy, and with CH2O on the right is how plant material is made. Diet Coke plus Mentos does produce an interesting effect, but this is not the way plants grow.

Tsunamis:

Can be predicted with some accuracy seconds to hours before the waves strike in most cases, allowing quick warnings to save many lives. 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.

Sediment is changed to sedimentary rock by:

Cementation by hard-water deposits, intergrowth of new minerals, and squeezing under the weight of additional sediment. Hard-water deposits are especially important in hardening coarse clastic deposits, especially sandstone and coarser. The finergrained deposits are more controlled by compaction under additional weight, and intergrowth of new minerals. But all of these processes can contribute.

One way that sediment is changed to sedimentary rock is by:

Cementation, a process that occurs in nature, and that is similar to processes that can occur in plumbing and other things humans make. Cementation, a process that occurs in nature, and that is similar to processes that can occur in plumbing and other things humans make.Feedback:Plumbers have big wrenches for a good reason. Water carries minerals, and where temperature or acidity or other things change, those dissolved minerals may be deposited, cementing things together.

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:

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. 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.

Regarding global warming, most scientists (including those who have advised the United Nations through the Intergovernmental Panel on Climate Change) agree that if we continue to burn fossil fuels at an accelerating rate:

Climate changes will primarily hurt poor people in warm places, but the climate changes are primarily being caused by wealthier people in colder places. Blizzards play havoc with airline travel, which hurts the economy in the mid- and high-latitude wealthier countries. If you have winter (so that warming reduces blizzards), air conditioners (so you can keep the economy humming when the weather is otherwise too hot for office work), and bulldozers (so you can build sea walls or haul things out of the way as the ocean rises), a little warming might even help your economy, although too much warming will be bad. If you are missing any of winter, air conditioning, or bulldozers, all warming is likely to be bad. Most of the world's people are missing all three, and will be hurt by warming, but the warming is being caused primarily by people who have all three.

The United Nations, under the auspices of the Intergovernmental Panel on Climate Change, has attempted to assess the scientific understanding of how greenhouse-gas emissions will affect the climate, and thus people. The UN reports show that if we continue on our present path, burning fossil fuels at a faster and faster rate:

Climate will change, primarily getting warmer, and those changes will primarily hurt poor people in warm places, but the climate changes are primarily being caused by wealthier people in colder places. Blizzards play havoc with airline travel, which hurts the economy in the mid- and high-latitude wealthier countries. If you have winter (so that warming reduces blizzards), air conditioners (so you can keep the economy humming when the weather is otherwise too hot), and bulldozers (so you can build sea walls or haul things out of the way as the ocean rises), a little warming might even help your economy, although too much warming will be bad. If you are missing any of winter, air conditioning, or bulldozers, all warming is likely to be bad. Most of the world's people are missing all three, and will be hurt by warming, but the warming is being caused primarily by people who have all three.

Volcanic eruptions cause many hazards to humans, and many geologists are employed to study these hazards and warn people. For a single, large, explosive volcanic eruption such as Mt. St. Helens, which of the following is not a worry that these volcanic-hazards geologists would warn people about?

Climatic warming, with the volcano causing a sudden heat wave that would harm people living in big cities.

Among fossil fuels:

Coal is made by heating of woody plant material, and oil is made by heating of algae. Slimy algae gives slimy oil; chunky wood gives chunky coal. Works great. Duct tape and WD-40 are the quick-fix tool kit; if something moves but it shouldn't, apply duct tape, and if something doesn't move but it should, apply WD-40. None of you would be so bad as to merit coal in your stocking, but we presume Santa gets it from a mine somewhere.

What cause probably was not important in contributing to extinction of most species on Earth, including the dinosaurs, in a very short interval of time at the end of the Mesozoic Era?

Cold from the change in Earth's orbit caused when the meteorite shoved the planet farther from the sun. Robert Frost once wrote "Some say the world will end in fire, some say in ice". For the dinosaurs, both were probably true, with acid thrown in. But the meteorite was not nearly big enough to change the planet's orbit noticeably. Frost went on "From what I've tasted of desire, I hold with those who favor fire, But if it had to perish twice, I think that for destruction ice, Is also great, and would suffice."

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:

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!). 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.

Which is not part of our modern view of geology?

Convection in the Earth primarily occurs in the lithosphere, and not in the deeper rocks. Convection occurs in the hot, soft rocks beneath the lithosphere, not in the relatively stiff, rigid lithosphere.

You find an atom, and you want to learn what element it is (its fundamental type). If you are efficient, you first should:

Count the number of protons contained in the nucleus of the atom. Physicists change the name when the number of charged, massive protons in the nucleus changes. Adding one proton makes a HUGE difference to how an atom behaves, and so deserves a new name. The neutrons hang around in the nucleus to keep the protons from kicking each other out. Exchanging electrons is important, but doesn't change the element type.

Subduction zones produce an amazing variety of geological features. These include

Deep trenches in the sea floor, formed by the bending of the downgoing plate, and sometimes filled with sea water but sometimes filled with sediment eroded from nearby land.

The North Pole sticks up out of Dr. Alley's bald spot, and the equator crosses his nose and cheeks. The sun shines on this odd globe, and on the real globe, the most likely thing that would happen here is:

Dr. Alley may get a sunburned nose, and the equator is hotter than the pole on the real Earth, primarily because the sun hits the equator directly but the sun hits the pole a glancing blow. GGeometry is the main control on equatorial heating. Although the equator is closer to the sun than the pole, the difference is tiny (about 4000 miles, with the distance from the sun to the Earth about 93 million miles, or about 0.004%) and matters little to the temperature difference between equator and pole (about 0.01oF, based on simple radiative equilibrium). 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.

The volcanoes of the island of Hawaii eventually will:

Drift off the hot spot and cease to erupt, while a new volcano grows to their southeast.

The picture shows some rocks on the beach at Olympic National Park. The pocket knife is about 3 inches (or 8 cm) long. What is the story of these rocks?

Earthquakes knocked loose undersea muds that raced down the slope into the subduction zone to make these layered rocks, which were scraped off the downgoing slab, part of the process by which continents grow as material is added to their edges at subduction zones.

Look at the picture above, from the coast of Olympic National Park. What happened here?

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.(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.)

Heat transfer by convection is:

Efficient through hot, soft rocks such as the deep mantle, but inefficient through outer space.

You are asked to assign as accurate a numerical age as possible (how many years old) to a sedimentary deposit. You would be wise to use:

Either counting of annual layers or radiometric techniques if the deposit is young (less than about 100,000 years), and radiometric techniques if the deposit is old (more than about 100,000 years). If you want an absolute date (number of years) rather than older/younger, you can count layers for young things, or use radiometric techniques for young things or for old ones. Uniformitarian calculations aren't very accurate.

You get in your Magic School Bus, drive down the throat of a volcano, and find that you are driving through melted rock that flows with much greater difficulty than does most melted rock, because the melted rock you are driving through is lumpier than typical for melted rock. It is likely that the melted rock you are driving through is:

Especially low in water and carbon dioxide compared to most melted rocks.

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:

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). 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.

Evolution produces new types, and extinction gets rid of them. The scientific evidence summarized in the text and in class shows that:

Evolution and extinction are usually more-or-less in balance, but occasional mass extinctions reduce biodiversity, and subsequent evolution faster than extinction increases biodiversity until a new balance is reached.

What is accurate about humans and extinctions?

Extinction has always happened naturally, but humans have accelerated the rate of extinction; both early humans and modern humans have contributed to extinction. Extinction has happened naturally, but humans have greatly accelerated the rate. Early humans caused extinctions, and so have modern humans, with real worries that the rate of extinction will accelerate a lot more in the near future

Religion and science always disagree.

False. Pope John Paul II said that the Catholic Church has no problem with evolution, and Baptist Jimmy Carter also supported evolution, so it is clear that religion and science can agree.

If you are drilling a well to reach water, you usually will have to drill:

Farther into the ground to make a deeper well on a ridge than in a valley. The water table hits the surface at streams and is near the surface close to streams, so only shallow wells would be needed in valleys. Water flows away from ridges to valleys, so the water table is deeper under ridges, requiring deeper wells. Water is found in much smaller spaces than caves in some rocks, so you don't need to hit a cave, and you really don't want to, as caves may be fasttrack paths for pollution and poisons from the surface.

Which one is younger:

Fault H. Unconformity L is cut by fault I, so is older than I. Fault I is cut by fault J, so is older than J. Fault J is cut by unconformity K so is older than K. Unconformity K is cut by intrusion G so is older than G, and intrusion G is cut by fault H so is older than H. Hence, fault H is the youngest.

If humans change the composition of the atmosphere in a way that would warm the world by one degree if everything else in the Earth system remained unchanged, most studies indicate that over the next years to decades:

Feedback processes will enhance this warming a little, causing the total warming to be a few degrees. Negative feedbacks stabilize the climate over long times of hundreds of thousands or millions of years or more, but feedbacks over years to millennia are mostly positive, amplifying changes. If there is a change in the sun, or CO , or something else sufficient by itself to raise the temperature by one degree, this will be amplified to a few degrees by feedbacks.

A glacier almost always flows:

From where the glacier's upper surface is high to where the glacier's upper surface is low. The great ice sheet of Greenland spreads from its central dome, so the ice on the south side is moving south, the ice on the north side is moving north, the east-side ice moves east and the west-side ice moves west. Ice flows down many mountains, such as Mount Rainier, but ice came across the Great Lakes and up into the US. Thus, ice flows from where its upper surface is high to where its upper surface is low.

As water from rain soaks through the soil, the water typically:

Gains carbon dioxide (CO ) from the air and then gains more carbon dioxide in the soil, becoming more acidic. CO 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.

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:

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.

Examine the two pictures above, labeled I and II. They are from the same sediment core collected in sea-floor muds from beneath the Atlantic Ocean off the coast of South Carolina. (The pictures are scanning electron micrographs by Brian Huber of the Smithsonian Institution, and the scale is the same on both, as shown at the bottom of each.) One picture shows a sample from just below the unique layer marking the extinction that killed the dinosaurs, and the other picture shows a sample from just above that unique layer.Which is which?

I is from below the unique layer, and II is from above the unique layer.

The above image is a satellite picture of Cape Cod. What is most accurate about the past and future of the Cape?

Glaciers built a pile of sand and gravel where rivers cannot sustain it, and the Cape eventually will disappear beneath the waves. The Cape is an end moraine attached to a medial moraine, built by the glaciers in an unsustainable place, and destined to disappear many millennia in the future.

Sedimentary rocks composed of clasts or chunks are usually subclassified by geologists based on:

Grain size—rocks made of big pieces are given different names than are rocks made of little pieces.Feedback:Small clay pieces make clay or shale, bigger silt pieces make siltstone, still-bigger sand pieces make sandstone, and so on. Almost all rocks contain iron and silica and other things, so the chemical classification doesn't work very well. Color is not often a useful indicator—rock colors change a lot during weathering, and often when oil or water move through. Mode of weathering is of interest, but isn't fundamental for the sedimentary rock.

The glacier shown above:

Has retreated, because a decrease in snowfall to the accumulation zone (A) or an increase in melting of the ablation zone (B) occurred. 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.

Volcanoes in Death Valley:

Have erupted recently (within the last centuries or millennia), showing that hot rock occurs at shallow depth beneath the valley.

Which of the following is not part of the evidence that the odd layer marking the extinction of the dinosaurs was caused by a large meteorite impact?

High concentrations of iron found in the layer.

What geologic setting is primarily responsible for producing Hawaii's volcanoes?

Hot Spot. The hot spot of Hawaii pokes through the drifting plate of the Pacific Ocean to make a volcano; then that volcano drifts away and the hot spot pokes through to make a new volcano.

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?

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

The consensus of the world's climate scientists, as generated by the UNsponsored Intergovernmental Panel on Climate Change (IPCC), is that:

Human activities have raised CO levels in the atmosphere, warming the planet, and the changes so far have been small compared to the changes that are likely over the next centuries unless we humans alter our behavior. Human activities have raised CO in the atmosphere, but if we continue with business as usual, we haven't seen anything yet— we haven't even doubled CO , but a quadrupling or even octupling seems possible. Chlorofluorocarbons used as refrigerants are responsible for the ozone hole, and cow flatulence is not greatly affected by external methane levels, which are rising in any case. Besides, bovine belching is a larger methane source than is outlet through the other orifice.

Which correctly gives the order of the faults, from oldest (first) to youngest (last):

I, J, H. I is cut by J, so I is older than J. And with reference to K, both I and J can be shown to be older than H.

During the most recent ice age:

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

Which of the following is not a part of the modern theory of evolution?

If the body of an adult living thing is changed by its environment, those changes usually are passed on biologically to children.

A University of Michigan student visiting Penn State's University Park campus drinks too much Diet Pepsi, wanders out in a pouring rainstorm, and takes a leak in a sinkhole behind the nearby Nittany Mall. The trout in the stream to which the sinkhole drains will notice the dastardly deed:

In a few hours to days. 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 pollution from Pennsylvania does not reach them. (Fun thing to do if you're bored: fit this question into the Michigan fight song.)

What is an important idea that geologists use to put sedimentary rocks in order from older to younger?

In a normal pile of sedimentary layers, the layer on the bottom is the oldest, and the layer on the top is the youngest.Feedback:A layer of sediment is deposited from wind or water or ice. Then, another is deposited on top—the wind does not reach down, pick up the "carpet" of a layer of dirt or rock beneath, and sweep a new layer underneath it.

The Cenozoic:

Is "new life", the age of mammals.Feedback:Ceno comes from the Greek kainos for new (the "cen" in "recent" has the same origin, and may make this easier to remember), and is the time when mammals came to be the dominant land animals. Although we are still in the Cenozoic, some people have suggested that we should change now to anthropozoic, or perhaps anthropocene, because humans are so influential now.

If you watched a sand grain moved by waves on a beach on the U.S. east coast, you would usually see that most of its motion:

Is alternately toward and away from the shore, causing little net change. 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.

Most commonly, a hot-spot volcano:

Is basaltic in composition, with gradual sides where the volcano projects above sea level, but steeper sides on undersea portions.

You get in your Magic School Bus, drive down the throat of a volcano, and find that you are driving through melted rock that does not make lumps but flows more easily than does most melted rock. It is likely that the melted rock you are driving through:

Is especially rich in water and carbon dioxide compared to most meltedrocks.

Using only uniformitarian calculations from the thickness of known sedimentary rocks, likely rates at which those rocks accumulated, and features in and under those sedimentary rocks, geologists working two to three hundred years ago estimated that the Earth:

Is more than about one-hundred-million years old. Radiometric techniques reveal the Earth to be about 4.6 billion years old, but early geologists did not have the sophisticated instruments to measure the trace radioactive elements and their offspring. Working from the rocks, the geologists knew that the age must be in the neighborhood of 100 million years, plus extra time in unconformities and additional extra time in the oldest, metamorphic rocks.

What happens to most of the water that falls on central Pennsylvania's Happy Valley each year (or any similar place, such as Washington, DC or other places with trees)?

It is re-evaporated, mostly after passing through trees. 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, but plants still get the majority. Flow 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.

Geological evidence based on several radiometric techniques has provided a scientifically well-accepted age for the Earth. Represent that age of the Earth as the 100-yard length of a football field, and any time interval can be represented as some distance on the field. (So something that lasted one-tenth of the age of the Earth would be ten yards, and something that lasted one-half of the age of the Earth would be fifty yards.) On this scale, how long is written history?

Just over the thickness of a sheet of paper. If the 4.6 billion years of Earth history are 100 yards, then the few thousand years of written history are just one-millionth of that history, just over the thickness of a sheet of paper.

Any region of limestone bedrock containing caves, sinkholes, springs, etc. is called:

Karst. Karst is the region of Slovenia (formerly in Yugoslavia) that has given its name to places with cave-related features. Many, many geological terms have been borrowed from other languages or places, including "geyser" from Icelandic and "tsunami" from Japanese. Permafrost is permanently frozen ground, Pepsoidal is a neologism for "of or pertaining to Pepsi", and scruty is just a word we made up so we wouldn't have to use Pepsi again. Sounds like some bizarre disease, anyway. "Stay back. I have scruty."

These two pictures are from Hawaii Volcanoes National Park, on the flanks of Kilauea Volcano. How are pictures I and II related?

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.

A grand piano in a house in one of the lowest-elevation regions of New Orleans protected by the human-made levees is:

Lower in elevation than a kayaker on the river when the river is carrying its average water flow. 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.

In the picture above, the dark stripes on the surface of the glacier are:

Medial moraines, rocks picked up from points where tributary glaciers flow together. The rocks are still in/on the ice, so they have not been deposited. Sedimentary layers would be spread over the surface like layers of paint, and mineral segregation would not act on such a huge scale.

What sort of rock is pictured above?

Metamorphic; The rock separated into layers as it was cooked and squeezed deep in a mountain range. The large crystals, intergrown nature, and separate dark and light layers all point to metamorphism, deep inside a mountain range. Rapid cooling in volcanic eruptions gives tiny crystals, not the big, pretty ones here. You can see the former sand grains or other-sized pieces in sediment and sedimentary rocks. And marmot doo-doo consists of small, dark pellets, akin to big rabbit doots, and usually isn't considered to be rock.

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?

Most of the damage is done by the few, big earthquakes.

Major differences between Mt. St. Helens and Hawaiian volcanoes include:

Mt. St. Helens is a medium-to-high-silica, explosively erupting stratovolcano, and Hawaii has low- silica, quietly erupting shield volcanoes.

Major differences between Mt. St. Helens and Hawaiian volcanoes include:

Mt. St. Helens is a medium-to-high-silica, explosively erupting stratovolcano, and Hawaii has low-silica, quietly erupting shield volcanoes.(The low-silica lava from the Hawaiian hot spot flows easily without large explosions, so the lava spreads out to make broad, gentle volcanoes that look like shields of medieval warriors. Melt a little basaltic sea floor with some water and sediment, and you get silica-rich andesite feeding explosive, subduction-zone stratovolcanoes such as Mt. St. Helens. Hot spots and spreading ridges make low-silica, basaltic volcanoes, which don't explode powerfully. Mt. St. Helens is a stratovolcano, but stratovolcanoes are steep, not broad and flat. Mt. St. Helens was the most active of the Cascades volcanoes even before its big 1980 eruption, and the volcano has erupted many times since the big eruption.)

Much less than the thickness of a sheet of paper. If the 4.6 billion years of Earth history are 100 yards, then the few thousand years of written history are just one-millionth of that history, just over the thickness of a sheet of paper. And your small piece of written history must be only a small fraction of a sheet of paper, roughly 1/200th or so.

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):

Narrower and shallower than it is today.

In the photograph above, a portion of cliff about 30 feet high is shown. From what location in the Grand Canyon did Dr. Alley take this image?

Near the bottom, where the river has cut through rocks that were cooked, squeezed, and partially melted deep in an old mountain range. This is the Vishnu Schist and Zoroaster Granite, rocks from the heart of a mountain range. The river is just barely out of the picture to the bottom.

If two drifting continents run into each other:

Neither will be subducted back into the deep mantle; instead, they will form an obduction zone. "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.

Newton's ideas on physics "won", and Aristotle's ideas were kicked out of science and over into history. Why?

Newton's ideas did a better job of predicting how nature would behave. Unlike painting or literature, scientific inquiry has a well-defined procedure for figuring out if Newton's ideas are better or if Aristotle had it right all along. In looking at a painting, we can ask different people what they think, or we can make up our own mind on whether we like it or not, and that is perfectly valid. In science, we have to ask: does the idea fit with the way the world works? Can I predict the speed of a falling object better using Newton's ideas or Aristotle's? As it turns out, Aristotle's ideas didn't predict things very well, and Newton's did.

Rocks in continents are on average much older than sea-floor rocks. The likely explanation is:

Old sea floor is recycled back into the deep mantle at subduction zones at the same rate that new sea floor is produced, but continents are not taken into the mantle and so remain on the surface for a long time.

A scientist gains knowledge about how the world works, and uses that information to successfully predict what will happen in an experiment. This proves that the scientist's knowledge is:

One or more of True, lucky, or close to being true (or cheating), but we can't tell which. If you guessed "heads" before a coin flip, and it came up heads, that would NOT prove that you can predict all coin flips; you will get half of such guesses correct by chance. You might be cheating, you might be lucky, or you might have figured something out.

Human population continues to grow. Looking at many of the things we use on Earth (farmland and land for wood and other things, fish in the sea, etc.):

Our use is large but not everything; we are approaching use of half of all that is available. We have removed perhaps 90% of the large fish in the ocean, and we raise crops or cut trees on much of the land surface. In very round numbers, we are approaching use of half of everything available on the planet, with the likelihood that we will greatly increase our population in the future.

What is accurate about seismic waves moving through the Earth?

P-waves (also called push-waves or sound waves) move through both solids and liquids

Geology departments are seeing a lot of recruiters recently, because geology is an in-demand major. Which of the following is NOT a job that geologists commonly end up doing?

Packaging substandard mortgages into "securities" and trying to sell them to unsuspecting people. Most jobs in geology involve finding valuable things: oil, clean water, ores, and more. But, geologists also teach and communicate in other interesting and entertaining ways, warn about hazards, and help understand the Earth system

Heating of some materials produces coal. With increasing temperature and time, one observes:

Peat, lignite, bituminous, anthracite. This is mostly memorization. But the names hide a lot of history, the peat-bog cutters of Ireland, the brown lignites now being mined in Wyoming, the deep-mines and strip-mines of the bituminous coals of western Pennsylvania, West Virginia and elsewhere, and the hard-coal anthracite of the Scranton and Wilkes-Barre region. If you don't know any of this history, you might consider reading up on it a bit; it is fascinating.

The pictures show famous volcanoes, that we discussed in the class materials. Which statement is most accurate about these?

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

The picture above shows the stem of devil's club, a plant of the northwestern coast of North America. The native people use devil's club for medicinal purposes. We now know that:

Plants protect themselves in many ways, including thorns but also through chemicals that are poisonous to many things that would eat the plants; those chemicals are sometimes harmful to humans (poison ivy, for example) but sometimes beneficial to humans, and have given us many of our medicines. Most plants have physical protections of some sort (hairs, thorns, hardened parts, bark, etc.), but almost all plants have chemical defenses. Those chemical defenses may kill us if we eat too much, but they also may kill microbes that would kill us before the chemicals kill us. A whole lot of our medicines have come from plants, and there undoubtedly are more to be discovered. There is a race on to find those new medicines before we exterminate the plants containing the medicines. Devil's club has been around longer than Pepsi has.

The above photograph was taken in the Grand Canyon, and shows a cliff that is approximately 30 feet high. What are the rocks in the cliff?

Precambrian metamorphic rocks with some igneous rocks intruded; the folding was caused by mountain-building processes when the rocks were very hot deep in a mountain range. This is the Vishnu Schist and Zoroaster Granite, rocks from the heart of a mountain range. The river is just barely out of the picture to the bottom.

The geologic time scale is, starting with the oldest and ending with the youngest:

Precambrian, Paleozoic, Mesozoic, Cenozoic. You could probably reason this out if you remember some Greek roots, or else just memorize it—Precambrian is oldest, then Paleozoic, Mesozoic and Cenozoic.

The picture above shows a view in the Earthquake Lake region just northwest of Yellowstone.The ramp or slope (often called a scarp) formed in an earthquake.What likely happened?

Pull-apart forces pulled the rocks apart, making the break, and allowing one side to drop relative to the other.

What tectonic setting is primarily responsible for producing Mt. St Helens?

Push-together Subduction. Mt. St. Helens sits above a subduction zone, where one tectonic plate goes below another as they come together.

The arrows point to an interesting feature, high in a road cut in the folded Appalachians of western Maryland. What happened here?

Push-together forces broke a layer during folding and shoved one side over the other side. 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.

What tectonic setting is primarily responsible for producing Olympic National Park as well as the hills on which San Francisco is built?

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

Soil thickness:

Reaches a natural balance between production by weathering and loss by mass movement, and humans have upset this balance, primarily by increasing mass movement so that soils are thinning.

Fossil fuels are usually formed from:

Remains of formerly living things buried by sediments in regions with little oxygen. Where oxygen is present in sediments, bacteria use the oxygen to "burn" organic materials, so oxygen and fossil fuels don't go together. And, Diet Pepsi is rather resistant to decay, and would not make fossil fuel.

The picture above shows a muddy limestone that was deposited in shallow water of a lake. The pocket knife is sitting on a high region of the rock. The pink arrow points along a low trough or groove in the rock, and several other such grooves are evident. The rock is:

Right-side-up; you are looking at the side that was facing up toward the sky when the rock was deposited.

Globally averaged, the level of the oceans is:

Rising, as warming causes the ocean to warm and expand, and as glaciers melt. Indeed, sea level is rising, by almost an inch per decade. The biggest reasons are melting of ice on land that releases water that flows into the ocean, and expansion of ocean water as it warms up.

Geophysical evidence indicates that convection is occurring in the Earth's mantle. What is the most likely physical explanation for why convection can occur in the mantle?

Rocks deep in the Earth expand and so become lower in density and tend to rise as they are heated, and the deep rocks are warm enough to flow slowly even though they are mostly solid.

You drill through the muds at the bottom of the sea floor and sample the rocks beneath, and you then determine the ages of those rocks, using standard scientific techniques. As described in the course materials, you will find that:

Rocks farthest from spreading ridges are oldest, with ages decreasing as you move toward a ridge.

Most earthquakes in the upper part of the Earth's crust are caused by elastic rebound, according to geologists. What do those geologists mean when they say this?

Rocks moving in opposite directions on opposite sides of a fault get stuck for a while and bend, then "snap back" when something breaks along the fault.

The two pictures above, I and II, show fossils inrocks from the Grand Canyon. Each is "typical"; the rocks near sample Icontain fossils similar to those shown in sample I, and the rocks nearsample II contain fossils similar to those shown in sample II. It is likely that

Sample I is from high in the cliffs of the Grand Canyon, and sample II is from much lower, near the river. Sample I is a wonderful shell hash, or coquina, from the Supai Rocks well up the side of the Canyon, and contains shells from a great diversity of different creatures. Sample II includes algal-mat deposits (stromatolites) from the Precambrian Chuar Group of the Grand Canyon Supergroup, deep in the Canyon near the river, from a time when biology was not a whole lot more diverse than algal mats. Lake Winna-Bango featured in the gripping Dr. Suess tale of Thidwick, the Big-Hearted Moose, but is not pictured here.

Opinion polls show most residents of the US do not believe they understand science very well, but they do favor more government support of science. Why do most US residents favor government support of science?

Science has helped make our lives healthier, wealthier, easier, safer, etc., and people hope that more funding of more science will provide even more health, wealth, ease, safety, etc. Without science and technology, the great majority of us would be dead, so we tend to be supporters of science. Although we know that science works, we're never sure that it is completely right. Students so often discover things that professors missed, or that professors got wrong, that scientists would be silly to claim Truth. Comparing the TV ratings of the latest hit to the ratings of the latest science program on public broadcasting shows that many Americans are not fascinated by science, but the science-show ratings are above zero, so some people are fascinated by science. And hope as we might, it is unfortunately clear that not every scientist is sexy (just most of them are...).

Years may pass with no major damage to the US mainland from hurricanes, but other years bring huge damages. A terrible event happened in 2005, when levees around New Orleans failed in the rising waters of Hurricane Katrina. More than 1400 people died, and the damages were in the neighborhood of $300 for each person in the US, or about $100 billion. As discussed in the text, history shows that:

Scientists and serious planners had warned about such an event for decades, based on the known size of hurricanes and the sinking of the Mississippi Delta and much of New Orleans. 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.

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:

Sculpting of the rocks by a glacier, which flowed from the left to the right. 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.

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:

Sea-level rise as the last ice age ended flooded river valleys to form bays, and sediment now is deposited in these bays rather than being delivered to beaches. Beaches lose sediment to deep water, and will shrink if the sediment is not replaced. Much sediment is now being trapped in the heads of bays such as the Chesapeake Bay, which formed from the end-of-ice-age sea-level rise flooding what had been the lower part of the Susquehanna valley. The sediment from the Susquehanna thus does not reach the Atlantic beaches, so as sediment is lost from them to deep water, they narrow, and waves cross the beaches during storms to erode the land behind to get sediment. 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.

In the picture above, 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?

Sediment has been eroded from the land by waves crashing against the bluffs, and the sediment has been transported along the shore by longshore drift to build the bar. 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. Submarines are not a big worry in such shallow, near-shore settings, and sinkholes tend to be round, not elongated as seen here.

Often, building a groin or "dam" sticking out into the water from a coast in a region where longshore drift is moving sand from "upstream" to "downstream" only partially solves the problem for which the groin was designed, because:

Sediment is deposited upstream of the groin but eroded downstream of the groin.

How is sediment related to sedimentary rock?

Sediment is gradually hardened to sedimentary rock by various processes, and the point where the name changes from sediment to sedimentary rock is somewhat arbitrary.Feedback:Loose sediments are known to be hardened in just a few years in exceptional cases, but usually thousands of years or longer are required (archaeologists usually excavate old sites using trowels and whisk brooms, not dynamite!). The change is usually gradual, and there is no sudden point at which the name changes.

In the picture above, the yellow arrow points at a jetty, a sort of sea wall or groin or dam, that was constructed along the coast of Washington. A likely interpretation of what you see here is:

Sediment transport is typically from the right, causing deposition to the right of the jetty but erosion to the left. A jetty works like a dam, trapping sediment on the "upstream" side and letting clean water pass to the other side, where the clean water erodes. So, the transport is typically from the right. A large beach has been formed there, but erosion "downstream" is cutting around the end of the jetty.

Which is not evidence that glaciers were much bigger about 20,000 years ago than they are now?

Shells of creatures that lived in the ocean about 20,000 years ago indicate that the ocean water was especially isotopically light then. 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, flooding river valleys and killing shallow-water corals as they lost their sunlight, but taking isotopically light water out of the oceans to grow ice sheets caused the remaining waters, and the shells, to be isotopically heavy.

The dominant large animals on Earth today are mammals. Before the giant meteorite impact 65 million years ago:

Small mammals coexisting with the dinosaurs were not able to outcompete the dinosaurs for big-animal jobs, but after the dinosaurs were killed, some large mammals evolved from small mammals to fill the large-animal jobs.

Mass wasting delivers sediment to streams. We believe that in regions such as Pennsylvania or the hills around Washington, DC, most of the mass that is delivered to streams arrives by

Soil creep, slow motion of pieces from freeze-thaw action, throw by falling roots, downhill motion of rocks during digging of gopher holes, etc. As rocks move to streams in many places, such as Pennsylvania or near Washington, DC, the slow and steady motions are more important than the few dramatic events. In very steep mountains, fast landslides may dominate, and slumps can be important, but although Pennsylvania does have both, they are not especially common. On the side of a sand dune, you often can see a dry grain flow. (If you've ever sat high on a beach and sifted dry sand through your fingers, you've made a grain flow.) But these are very rare in Pennsylvania or near DC, where the soil tends to stick together even in summer. And while there may be careless people who misbehave in sinkholes, this won't get too many rocks to streams.

Before they can be published, scientific papers must be peer-reviewed. This means that:

Some other scientific experts read the papers and provide quality control by eliminating many mistakes. Reviewers work hard to identify errors of any sort, almost always identify many, and then the reviewers and editors insist that those errors be fixed before publication. Review is done voluntarily by scientists; this is part of the cost of being a member of this great human undertaking. Science doesn't claim Truth; although science strives to be as accurate as humanly possible, that is often well short of Truth.

Beaches change size with every storm, but if you average over a few decades, the size of a typical sandy beach is usually controlled by:

The balance between sand loss to deep water, and sand supply from rivers or from coastal erosion.

What is accurate about the scientific results learned by counting tree rings?

Study of tree rings and associated geology shows that the Earth is more than 12,429 years old. The longest continuous tree-ring record is 12,429 years, but that was published a few years ago, the trees grew in soil that was already there, and there is lots of older wood around. So, the tree rings show that the Earth is more than 12,429 years. But, we don't have overlapping trees back to the formation of the Earth about 4.6 billion years ago, so tree rings do not show that the Earth is 4.6 billion years old.

The scientific study of the origin of the planet has taken a lot of effort, and still generates much discord outside the scientific community although almost no discord within the scientific community. The scientifically accepted history is:

The Earth formed from older materials that fell together under gravity about 4.6 billion years ago. The Big Bang is estimated as having occurred about 14 billion years ago. Stars that eventually formed in the wake of the Big Bang led to production of elements such as iron and silicon that are common in the Earth—we are formed from second-generation stardust, which "got it together" to make the planet about 4.6 billion years ago.

What is more accurate about the Earth?

The Earth is formed of concentric layers (something like an onion--a central ball with a shell around it, and a shell around that...); when the planet melted, it separated into layers. The planet is onion-like, with an inner core, then an outer core, a mantle (which has several sub-layers), and a crust. The moon-making collision did happen, but the planet got hot enough to separate again. The planet separated after melting largely or completely, with the densest stuff falling to the center and the lowest-density stuff floating to the top.

In the picture above, when Dr. Alley slices his finger through the sand, he is recreating on a smaller scale what type of geologic process?

The action of mass wasting, as soil and rock collapses off of newly steep canyon walls initially carved out by water. Despite any passing resemblance, Dr. Alley is not using martial arts techniques to extract money from sand. Instead, he is showing how a river carves a canyon, which then widens as mass wasting occurs on the steep new walls.

Your boss has assigned you to get the low-down on the latest wonder-drug and to be darn sure to get it right. You would be wise to consult:

The article in the Journal of the American Medical Society, a peer-reviewed scientific journal, reporting on the discovery and testing of the drug. No source of information is perfect, but the refereed articles in learned journals put immense effort into "getting it right". The web has some reliable information, but probably most of the information on the web is not especially reliable. The web is very inexpensive, and lots of people put junk on it. The Wikipedia gets a lot of things right, but it is a distilled synopsis of the real stuff. Most newspapers are around for the long haul, and try to make the news fairly accurate, although some newspapers do have agendas, and the editorial pages are not especially accurate. But, if the report is on the views of a public figure, the newspaper may accurately report what the public figure said, but what the public figure said may be less than completely accurate. And while you are welcome to believe that an unsolicited email promising to grow your ***** will do so... don't count on it.

What is the "Ring of Fire"?

The complex of volcanic arcs fed by subduction zones encircling the Pacific Ocean.(The "Ring of Fire" is the circle of volcanic arcs fed by subduction zones with scraped-off muds and deep earthquakes around the Pacific Ocean)

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?

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. 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.

Melting happens in association with a subduction zone. What is going on to cause this?

The downgoing slab takes along water, and that water lowers the temperature at which rock melts to allow melting in and near the slab.

Volcanoes occur above the downgoing slab of a subduction zone. Why?

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

Large rivers have many interesting features, including:

The flood plain, the nearly flat region farther from the river than the natural levees and composed of mud deposited by the river's floods. Many processes contribute to the formation of flood plains, but deposition of mud to smooth the surface is the most important one. Flood plains often occur beyond natural levees. The initial slowdown as floodwater spreads from a river channel into the trees deposits sediment to form natural levees

The cartoon above illustrates a specific geologic process. Which of the additional geologic images DOES NOT feature this same process at work?

The folded Appalachians, including the region of central Pennsylvania around Penn State's University Park campus, shown in the satellite image here, as well as the Great Smokies and the Blue Ridge, formed when Africa and Europe collided with the Americas, much as the two cars in the picture collided. Crater Lake records different processes.

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:

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. 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.

On the Richter scale of earthquake intensity:

The ground is shaken 10 times less by a magnitude-4 quake than by a magnitude-5 quake.

Air that passes over the Sierra Nevada from the Redwoods to Death Valley is warmed by roughly 30 F, even if the air goes over at night. Where does the energy come from?

The heat that had been stored during evaporation of water from the ocean and was released when condensation made clouds and rain over the Redwoods. 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. Winds are driven by pressure differences, and do curve in response to the Earth's rotation, and there is a little bit of heat generation from friction, but you should probably know that standing outside in the wind does not make you hot as the frictional heating occurs around your body—the frictional heat is very small. (If the air were moving past you at many times the speed of sound, the frictional heat would become large, as shown by meteorites "burning up" in the atmosphere, and the need for heat shields on spacecraft re-entering the atmosphere. And while marmots do produce a little methane, and a bit of heat, they don't produce nearly enough to matter to the climate.

Dave Janesko holds two rocks next to each other.The black one (to the upper left in the picture) is from a lava flow, and is much younger than the red one (to the lower right in the picture), which is a lake sediment. In nature, these rocks are found the way Dave is showing, with the younger black one next to the older red one rather than being on top of the older red one. This actually is related to Death Valley, although these rocks are a good bit east of Death Valley.As described by Dave Janesko in the online video, what happened here?

The lake sediments were deposited, then the lava flowed on top, and then a pull-apart Death-Valley-type fault formed, breaking the rocks and dropping the lava flow to be next to the lake sediments.

What is accurate about a typical volcano formed by eruptions from a hot spot?

The lava of the volcano is mostly basaltic in composition, with gradual sides where the volcano projects above sea level, but steeper sides on undersea portions.

In Pennsylvania today (or at most other places on the world's land surface):

The land surface is accumulating sediment in a few small places, building up records of geologic history, but most places are eroding.

Look at the picture above. Here is new land forming in Hawaii, where lava enters the sea. What is happening here?

The lava flow has cooled on the sides and is draining out the middle. Eventually, if more lava is not supplied at the other end of the tubes to replace the lava that is draining out, the lava tubes may empty and leave caves.

Which is accurate about the Earth?

The lithosphere is a layer containing both the uppermost part of the mantle and the crust, where breaking is more common than flowing. The lithosphere is the soft part of the mantle below the asthenosphere. The asthenosphere is a layer containing both the hottest part of the mantle and the crust, where flowing is more common than breaking.

Most of the island of Greenland is covered with a great ice sheet, but rocks and soil stick out in some coastal regions, such as the one in this picture in the great Northeast Greenland National Park. The picture above shows a hillslope 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?

The materials on the hillside are moving toward you at an inch or so per year. 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.

Dr. Randall Irmis is a famous paleontologist, who has gone on to make important discoveries since he showed the Penn State CAUSE class this fossil plate from the armored vertebrate Buettneria. Based on the discussions in the class materials on the topic of evolution, it is likely that:

The most similar species alive today are related to but recognizably different from Buettneria.

Earthquakes can be caused in many different ways. The best interpretation of the planet's earthquakes is that:

The rare, deepest ones are caused by "implosion" as minerals in downgoing slabs of subduction zones suddenly switch to a denser arrangement, whereas common shallower ones are caused by elastic rebound of bent rocks when a fault breaks.

The picture above shows a very hard piece of rock about six inches across, in the Grand Canyon. The surface of the rock looks rather different from the surfaces of many other rocks. What made this odd-looking surface?

The river, which blasted the rock with sand- and silt-laden water during floods; this shows that even hard rocks can be eroded by rivers. The Canyon was carved by the Colorado River. Glaciers have not been there, and while wind and faults can change the appearance of rocks, none makes something like this river-polished rock, as you saw in one of the Grand Canyon V-Trips.

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?

The rock was carried here by glacier ice and left when the ice melted. 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.

Suppose you wrote a big check to someone to go out into deep water and haul sand up to replenish your private beach along the Atlantic coast. What is this most likely to cause?

The sand will be moved back into deeper water by waves and currents over the next year or years. Waves and currents move lots of sand. If we want to offset this, we need to move a lot of sand, too. Building beaches from mined sand can work, but the sand heads back to deep water quickly, so in most cases the activity must be repeated every year or every few years to keep the beaches large and sandy

You use highly accurate techniques to learn the time when lots and lots of di erent volcanic rocks solidified from melted rock. You do this for many di erent rocks across the continents, and many di erent rocks across the sea floor. You will find that (note that "older" rocks are those that solidified more years ago, and "younger" rocks are those that solidified fewer years ago.):

The sea-floor rocks are typically younger than the continental rocks, because sea-floor rocks are taken back into the mantle at subduction zones about as rapidly as new sea-floor rocks are produced, while continental rocks are not taken back into the mantle at subduction zones.

You use highly accurate techniques to learn the time when lots and lots of different volcanic rocks solidified from melted rock. You do this for many different rocks across the continents, and many different rocks across the sea floor. You will find that (note that "older" rocks are those that solidified more years ago, and "younger" rocks are those that solidified fewer years ago.):

In the image above, a stream from the land on the right enters the ocean on the left in the lower part of the picture, and another does the same near the top of the picture. What happened where the streams met the ocean?

The sediment carried by the streams settled out in the slower-moving ocean water, forming deltas that built up as they built out so that they still slope slightly downhill toward the sea. These deltas in a fjord in Greenland are like any other deltas; the deposits cannot be purely flat-topped, or the rivers would not flow across to get to the sea water in the fjord.

Chemical reactions involve:

The sharing or trading of electrons. The clouds of electrons around the nuclei of atoms serve as the Velcro of the universe. Atoms gain or lose electrons and then stick together by static electricity, or else share electrons and stick together inside the shared cloud. The nuclei with their protons and neutrons (which are themselves composed of quarks, which also were called partons at one time) are the things held together by the electronic Velcro of chemistry.

One practical radioactive system used to date lava flows involves:

The solid potassium-40, which decays to the gas argon-40. Potassium-40 is common in solid minerals, and decays to produce the gas argon-40. And despite his great contributions to humanity, no one has named an isotope after moose moss (the favorite food of Thidwick, for you Dr. Suess fans).

The concentration of CO in the atmosphere rose as the last ice age ended, and then stabilized for thousands of years, until humans became serious about changing the atmosphere with the start of the industrial revolution. Suppose that we succeed in raising the CO concentration in the atmosphere to a level twice as high as occurred for the thousands of years after the ice age and before the industrial revolution, and then we hold the concentration constant at that new, higher level for the next thousand years. What would happen to the average temperature of the planet?

The temperature would increase to a few degrees above the preindustrial-revolution level, and then stabilize at that new, warmer level. Doubling CO is estimated to warm the Earth by between 1.5 and 4.5 C, or 2.7 to 8.1 F, with some chance of slightly larger change and very little chance of smaller change. The physical basis of warming from CO is quite well understood, and cooling or no response is very unlikely. You might compare the expected warming from CO to getting up to put another blanket on the bed in the night if you are cold. True, you might spill a glass of water into the bed, or your significant other might steal the other blankets while you're up, so getting the extra blanket might make you colder, but common sense says that getting the extra blanket warms you. Warming from CO is about as certain as warming from the extra blanket—maybe a huge number of volcanoes will explode in the near future and offset the effects of the CO , but don't count on it.

You are told that you are going to visit a region that was under a glacier for many thousands of years ending about 20,000 years ago, but was near where the glacier ended by melting, so lots of meltwater streams flowed through the glacier to the bed and out the front. What will you probably find in the landscape?

The tracks of the glaciers will be easy to see, although minor modification by streams, wind and mass movement will have started. "Wet" glaciers, those with much meltwater, modify the landscape faster than do streams, wind or mass movement in most cases, but streams and wind and mass movement do make a difference over thousands of years or longer. So the glacier tracks from 20,000 years ago remain clear but are starting to be modified by other processes.

What probably happened in the above picture?

The tree started with its roots underground, but erosion washed the dirt away from them, so now they stick out. Erosion can be rapid in steep places with weak rocks, such as here on the rim of Bryce Canyon, uncovering formerly-underground tree roots. In wet places, you sometimes can observe a tree growing on an old stump, but this is a somewhat dry site with no evidence of stumps to be used for such a purpose, and the Park Service would not come in and root out a stump from under a tree. The park service promotes nature, not human sculpting of trees. This is not a Jeffrey pine, and pines in general do not grow multiple trunks. But a lot did happen here, and is still happening.

Which is younger:

The tree. The tree is growing on intrusion G, which can be shown to be younger than all of the others.

In the bottom of Death Valley, you will find layers of gravel deposited by rivers. Based on materials presented in class, what is a likely explanation for this occurrence of river gravels in the valley bottom?

The valley was dropped relative to the mountains by faulting, and rivers now are carrying gravels down from the mountains into the valley and depositing the gravels at the valley bottom.

Statistically, and based on how many people are likely to die if they engage in or are exposed to the following problems, which is most dangerous to residents of the United States:

The various diseases that come from smoking, overeating and under-exercising for a long time.

Above is a "beach" at Acadia National Park. The pieces are granite.

There is no sand here, so sand must be lost to deep water fast enough in comparison to sand supply that sandy beaches have not formed. Granite does weather to make sand, so some sand must be produced, but this is not a sand deposit, so sand loss must be fast enough to prevent large accumulations. The Park Service neither mines sand from beaches, nor hides sand on beaches. And huge storms hit Florida and the Gulf Coast, but they have sandy beaches.

The photograph above shows some rocks in Great Smoky Mountains National Park. From looking at the rocks, and what you know about the park, a likely story is that:

These rocks were buried deeply and squeezed in a continent-continent collision, and then brought to the surface as overlying rocks were eroded. The squeezing and heating of an obduction zone have changed these rocks from mud to the folded schist seen here, and then erosion has revealed the rocks at the surface. There were large volcanoes near where the Smokies are before the Smokies formed, but those volcanoes ended when subduction ceased and obduction started to build the Smokies. Some slide-past motion did occur in the Appalachians, but not a huge amount, and the Smokies were not brought up from Florida.

What do the ptarmigan and the marmot below have in common?

They are both standing on glacially eroded surfaces. The carbon-based bird, top, would be unhappy if you accused him of being a silicon-based flatulent mammal. Periglacial cryoturbation produces sorted stone circles, and glacial deposition makes till or outwash. The striated, polished granites under these cold-climate critters were eroded by glaciers.

Look at the picture above of a small dam across a stream bed (between the pink arrows) just above one of the trails into Bryce Canyon.When floods happen in the stream bed:

They flow toward the camera; floodwaters have filled the space upstream of the dam and debris has started to cascade over the dam, so the dam is not serving to trap sediment any more.

One of the big problems faced by National Parks is that:

They must allow people to enjoy things today, and preserve those things for the future, but achieving both of these is not easy. The law that established Yellowstone as the first national park required "conservation... unimpaired for...future generations" and "to provide for the enjoyment" of the parks. But what if so many people want to visit that they scare the wolves, or trample the soil and kill the roots of the big trees? Enjoying and preserving at the same time isn't easy! Fortunately, caffeinated chipmunks and maritally distressed moose are not big problems.

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?

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.("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.)

The things that glaciers deposit include:

Till (which is unsorted) and outwash (which is sorted). Striations, polish, cirques, hanging valleys, and roughdownglacier/rounded-upglacier (not vice versa) bedrock knobs are all features of glacier erosion, not deposition. Till, deposited directly from the ice, includes pieces of all different sizes because ice can carry all sizes without sorting by size; outwash is washed out of a glacier by meltwater and sorted by size.

John Wesley Powell, who led the first boat trip through the Grand Canyon, called the feature marked by the yellow lines "The Great _________". What did he put in the blank?

Unconformity. This is The Great Unconformity, separating inclined sedimentary rocks below from horizontal sedimentary rocks above. The rocks above are from the Paleozoic, and those below from the Precambrian. A Trompe L'Oeil painting is designed to fool the eye, but this is real.

The "Law" of Faunal Succession:

Was developed by an engineering geologist to aid in construction projects. In the late 1600s in England, William Smith discovered that putting the rocks in time order put the fossils in time order, allowing him to use the fossils as a shortcut in understanding the rocks. We will see soon that faunal succession is consistent with evolution but does not require it, does not require but might allow catastrophism, and informed but was not developed by theoretical biologists. Faunal succession was known before Congress was founded.

In the picture above, Dr. Alley is on the South Rim of the Grand Canyon. What problem with the Canyon is he discussing?

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. 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.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.

At the beach, you can build really good sand castles

When the sand is damp, because water is attracted to sand grains and to other water; thus, pulling sand grains apart when damp requires "breaking" the water, which is not easy. Any good glue must stick to other things and to itself. If it doesn't stick to other things, the glue just peels off. If it doesn't stick to itself, you can break the glue in the middle easily, separating the things that you just glued, although leaving a little glue on those things. Water works the same way—it sticks to sand grains well, and water molecules are attracted to each other, so that it takes some "oomph" to break apart damp sand grains. Make them fully wet, and the grains can move without "breaking" the water, so the material becomes weak.

Which of the following was probably important in contributing to extinction of most species at the same time the dinosaurs became extinct?

Wildfires caused by great heat from rocks warmed by atmospheric friction while falling back to Earth after being blasted high in the atmosphere by the impact.

A dam is built on a river that has a river bed that is primarily sand. You have a house just downstream of the dam, and you like to go trout fishing in the river in front of your house. A few years after the dam is built, it is likely that:

You will have built a ladder or steep path to get down to the river, because the clean water released by the dam will have washed a lot of the sand away and lowered the elevation of the river in front of your house. 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. Meanwhile, moving water can carry sediment. Sediment-free water is released from a dam but often later observed to have sediment, so erosion must be occurring. Loss of sand bars below the Glen Canyon Dam shows that sand is carried away downstream of dams. Dams stops floods that are needed to move the big pieces (boulders, cobbles), and dams cause sedimentation upstream, while erosion occurs downstream.

You develop a new idea, which is in conflict with a widely accepted scientific idea. For your new idea to gain widespread acceptance, you probably will need to show that:

Your new idea does a better job than the previously accepted idea in predicting the outcomes of an interlocking web of important experiments or observations.

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