Geo 10 Final

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.

What do we know about the effects of humans on extinction of plant and animal species on Earth?

Both prehistoric and modern humans have been responsible for extinctions.

• What happens to the rain that falls on central Pennsylvania each year?

most evaporated

You start with 200 parent atoms of a particular radioactive type, which decays in a single step to give a stable offspring, and you start with none of those stable offspring. You wait just long enough for two half lives to pass. You should expect to have how many offspring atoms (on average)(remember that the number of parents and the number of offspring add up to 200, so if you have 10 parents, you have 190 offspring because 10 and 190 add up to 200, and if you have 20 parents you have 180 offspring, and so on):

150

• 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

You start with 400 parent atoms of a particular radioactive type, which decays to give stable offspring. You wait just long enough for three half lives to pass. You should expect to have how many parent atoms remaining (on average):

50

The great diversification of shelly fossils that marks the beginning of the Paleozoic Era occurred about:

570,000,000 years ago.

Acadia National Park has a long, rich and varied geologic history. The large island marked "I" in the middle of the above picture is composed of resistant granite from the long-ago closure of the proto-Atlantic. However, the shape of the island was formed by much more geologically recent processes (within the last 100,000 years or so). What is primarily responsible for the beautiful shape of the island?

A glacier flowed over the island, moving from left to right, smoothing the rocks encountered first and plucking rocks free from the other side.

• The extinction of many types of dinosaurs occurred about:

o 65,000,000 years ago

Look at the picture above. What happened here?

A great volcanic explosion occurred, spreading material across the landscape, and the hole left behind after the eruption later filled with water.

The Marcellus shale is:

A major new source of gas that has become available because people developed the technological tools to recover the gas.

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.

Oxygen (O2) and nitrogen (N2) do not have much greenhouse effect, but several trace gases including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and various chlorofluorocarbons are important greenhouse gases. The primary mechanism by which these greenhouse gases warm the Earth is:

Absorbing some of the infrared radiation emitted from the Earth.

Humans (and our crops and pets and farm animals) now use:

Almost half of the things the planet makes available and that we like to use.

The picture above shows Telescope Peak, towering above Death Valley. The straight edge of the alluvial fan in the foreground is:

An earthquake fault, where the valley has dropped relative to the mountains.

The picture above shows a beautiful specimen of Araucarioxylon arizonicum, a fossil tree from the Mesozoic rocks of Petrified Forest National Park. Based on the discussions of evolution in the class materials, it is likely that:

Araucarioxylon arizonicum is related to, but recognizably different from, trees still alive today.

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

• 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 down (which letter is closest to the arrow that is pointing in the direction you would have looked to see the ground when the dune was deposited)?

B

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.

The sea floor that forms at spreading ridges and then moves away will

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

Extinction removes biodiversity, and evolution generates biodiversity. The balance between extinction and evolution controls the Earth's biodiversity. Based on the scientific evidence summarized in the text and in class:

Biodiversity fluctuates about a balance, with short-lived mass extinctions lowering biodiversity and subsequently evolution exceeding extinction over tens of millions of years to increase biodiversity until a new balance is reached.

Which formula most closely describes the process by which plants make more of themselves:

CO2 + H2O + energy → CH2O + O2

During the most recent ice age:

Central Pennsylvania was just beyond the edge of the Canadian ice.

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.

Heat transfer by convection is:

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

Among fossil fuels:

Coal is made by heating of woody plant material, and oil is made by heating of alga

The processes that made Death Valley continue to operate today. For this question, ignore the sand and gravel moved by water and wind, and think about the big motions of the rocks beneath. Choose the best answer: what are they doing to the valley?

Death Valley is getting wider and deeper.

Some eruptions come out of volcanoes really rapidly and shoot really high because:

Dropping pressure as the melt rises allows volatiles including water vapor and carbon dioxide to make bubbles that lower the density and make the melt rise even faster.

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.

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.

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.

Evolutionary theory is used in the real world for:

Fighting diseases, and in other practical ways including guiding some techniques in computer science.

The jobs of geologists include:

Finding valuable things in the Earth, warning about hazards, learning how the Earth works, and educating and entertaining people.

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.

Which of the following is part of the evidence that the odd layer marking the extinction of the dinosaurs was caused by a large meteorite impact?

High concentrations of iridium found in the layer.

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

Human activities have raised CO2 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.

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 that is just older than the unique layer marking the extinction that killed the dinosaurs, and the other picture shows a sample that is just younger than the unique layer. Which is which?

I is older than the unique layer, and II is younger than the unique layer.

Which of the following is part of the modern theory of evolution?

If a reproductive "experiment" is successful, it will be passed to more and more children in successive generations until all members of a population have it.

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.

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 far on the football field would represent the time between the first appearance of abundant shelly creatures and today?

Just over 10 yards.

It would be really nice to know whether an earthquake is coming, so we could prepare for it. At this time, we are able to:

Make reasonably accurate estimates of where earthquake damage is likely, and how bad earthquake damage is likely to be, but not exactly when an earthquake will occur.

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.

Science professors teach certain theories and not others (Newton's physics, and not Aristotle's, or Darwin's evolution and not Lamarck's). If you were to ask the professors why, a majority would tell you (more or less; not using exactly these words but with this meaning):

Nature has repeatedly been asked (through experiment) which is better, and we are teaching the ones that made successful predictions, and not teaching the ones that failed."

At current rates of use, and at prices not greatly higher than those of today:

Oil will run out in a century or so, and coal will run out in a few centuries.

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.

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

Peat, lignite, bituminous, anthracite.

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)?

Piled up mud and other things scraped off the slab being subducted

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.

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

In age dating, geologists use:

Radiometric techniques and layer-counting for absolute dating of events that happened in the last 100,000 years, and other radiometric techniques for absolute dating of much older events.

Reasons why fossils of transitional forms are missing in some lineages that humans especially care about include:

Rapid evolution often occurred in small populations, and fossilization is less likely in smaller populations.

What is accurate about the scientific results learned by counting tree rings and other annual layers?

Records in tree rings, lakes and ice all reach beyond 12,000 years, and some of them reach beyond 40,000 years.

National Parks are:

Regions containing key biological, geological or cultural resources that have been set aside for the enjoyment of the present generation and future generations.

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.

When discussing earthquakes that happen in the upper part of the Earth's crust, geologists believe that most are caused by elastic rebound. This means:

Rocks on opposite sides of a break, or fault, move in opposite directions, get stuck against each other for a while, bend, then "snap back" when something breaks or gives along the fault.

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.

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.

Glaciers form where:

Snowfall exceeds melting for a long enough time.

Think about Pennsylvania, or other places in the eastern US. What is accurate:

Sediment is accumulating in a few places, with erosion in most places, and this has been the pattern for a long time, so the geologic record in any township or similar-sized area is notably incomplete, and you need to combine observations from many places to get a reasonably complete geologic record.

Humans often try to change coastal processes to benefit us. One of the many things we do is to build walls, or groins, or jetties, to interrupt waves and currents and sediment transport. This example is from the coast of Washington. What has happened here?

Sediment transport is typically from the right, causing deposition to the right of the jetty but erosion to the left

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 childhood stories (such as Little Red Riding Hood), we humans worry about predatory mammals such as wolves or tigers rather than worrying about predatory dinosaurs such as allosaurs or tyrannosaurs. This is because:

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, including the big-predator job.

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.

Hardy souls who visit beaches in the winter are often surprised by how different summer and winter beaches really are. A typical change is (note: a breaking wave curls over and the top falls down, making spectacular movie footage if a surfer is in the way; a surging wave hangs together and the top doesn't fall over):

Surging waves bring sand in during summer, and breaking waves take sand out during winter, so summer beaches are large and sandy while winter beaches are small and rocky.

Suppose that CO2 in the atmosphere was held at a constant, natural level for a few thousand years. Then, CO2 was added to double the atmospheric level rapidly, and this new, doubled level was maintained for a few thousand years. What was the most likely change in the typical average temperature of the planet?

Temperature after the increase in CO2 was a few degrees higher than temperature before the increase.

The Earth has a fascinating history, which this class has just begun to explore. Which is more nearly correct, according to the scientific interpretation presented in the text?

The Earth formed about 4.6 billion years ago, well after the Big Bang, as materials made in stars fell together to form the planet.

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.

We humans are changing the composition of the atmosphere in many ways. Those changes will directly affect the planet's temperature, but the resulting change in temperature will affect other things on the planet that also affect the planet's temperature. Suppose that we could magically change the composition of the atmosphere enough to raise the temperature one degree if all other parts of the Earth system were held fixed, and after the warming, we allowed the other parts of the Earth system to react for a few years or decades. At the end of that time, what would be the total change in the Earth's temperature?

The Earth would end up a few degrees warmer than before the human influence, because positive feedbacks would amplify the original change.

There is a deep trench in the sea floor off the Marianas volcanic arc of explosive, andesitic, Ring of Fire volcanoes in the South Pacific, but the water is not deep off the coast of Oregon and Washington near Mt. St. Helens and the Olympic, because:

The Marianas, Oregon and Washington have had the sea floor bent downward by subduction to make trenches, the trench off Oregon and Washington is filled by sediment eroded from the nearby continent, but the Marianas don't have a nearby continent and so the trench there is not filled with sediment.

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.

Which is accurate about the Earth?

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

Most of the material moved by volcanoes is from the few, big ones rather then from the many, little ones. Most of the material moved downhill in landslides is in the many, little ones rather than the few, big ones. In comparing the importance of the few, big earthquakes to the many, little earthquakes, are earthquakes more like volcanoes (the few big ones matter most) or like landslides (the many little ones matter most)?

The few, big earthquakes matter most (like volcanoes).

On the Richter scale of earthquake intensity:

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

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.

Often, landowners along eroding beaches will build groins, which are walls or dams sticking out into the ocean or lake from the beach. Why are these built, and what happens?

The landowners are trying to catch sediment from the longshore drift to add to the beach; this can work, but often erosion on the "downstream" side of the groin makes the neighbors mad.

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.

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.

The low bluffs show that erosion has been occurring as waves hammer the shore, and the bar shows that longshore transport is moving the sediment from that erosion along the shore.

In chemistry, the type of an atom (what element it is) is determined by:

The number of protons it contains in its nucleus.

The United Nations-sponsored Intergovernmental Panel on Climate Change shared the 2007 Nobel Peace Prize. The information that the Panel has supplied to policymakers includes

The observed rise in atmospheric CO2 levels has been caused primarily by human fossil-fuel burning, and very likely is causing warming of the climate that is likely to become much larger if we continue our current behavior.

Which is not accurate about the Grand Canyon, in Arizona:

The oldest rocks are on top, with younger ones beneath, as shown by all of the footprints being upside-down in the rocks of the canyon walls.

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.

Dust and shells and fish poop and all sorts of things fall to the sea bed to make sediment. Across broad central regions of the ocean, the sediment accumulates at a uniform rate—piling up about as rapidly here as it does over there. And, in most places, the currents don't move the sediment around much, so that it stays where it falls. Thus, the thickness of the sediment is related to the age of the rocks beneath the sediment. If you go around an ocean and measure the thickness of the sediment in lots of places, you are likely to find:

The sediment is thin near spreading ridges, and thicker away from the ridges.

Chemical reactions involve:

The sharing or trading of electrons

One practical radioactive system used to date lava flows involves:

The solid potassium-40, which decays to the gas argon-40.

You build and maintain two biologically diverse terrariums that are identical in every way at the beginning, except that one is divided in half by an unbreachable glass wall. After some time (long enough for many generations to pass, but not long enough for much evolution to occur), it is most likely that:

The undivided terrarium will have more species than the divided one.

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.

People visit Death Valley for all sorts of reasons. Some people even go there to study volcanoes. What is accurate about those Death Valley volcanoes?

The volcanoes near the edges of Death Valley produce rocks that are similar in composition to the rocks made by volcanoes at undersea spreading ridges, because Death Valley is in many ways geologically linked to undersea spreading ridges.

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

They are both standing on glacially eroded surfaces.

What happens to most living things, after they die?

They are recycled, usually by being "burned" with oxygen to provide energy for other living things, or to provide energy to fires.

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.

Your friend wants to see some real Pennsylvania coals. Where should you send your friend to see coal in the rocks of Pennsylvania (if you honestly are being helpful), and what coals would your friend see?

To the sedimentary rocks of western Pennsylvania to see bituminous, and to the metamorphic rocks of eastern Pennsylvania to see anthracite.

The picture above shows a region of hard rock about six inches across from the Grand Canyon. The shape and polish of the rock are interesting. It is likely that the rock

Was scratched and polished by silt-laden river water, during carving of the Canyon by the Colorado River.

The law that established Yellowstone as the first national park:

Was written to help people today and in the future, by requiring that the parks provide enjoyment today while preserving the parks for the future.

If you could drill a hole straight to the center of the Earth, and keep track of what the hole is going through, you would find:

You would go through one sort of material, and then a different, denser material, and then a still-different, still-denser material, because the planet is made of concentric layers, sort of like an onion.

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.

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

Look at the picture above. What type of volcano is this?

a. A subduction-zone-type, steep andesitic stratovolcano

The volcanoes of the island of Hawaii eventually will:

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

The best description of a scientist's job is that she or he:

a. Invents new ideas, and shows that some ideas are false.

The final arbitrator between two alternate theories (for example Aristotle's and Newton's ideas) is:

a. Nature, and experiments conducted to test each idea.

The US government, and most other governments of the world provide support for scientists but not for astrologers, palm readers, or telephone "psychics". Why do governments support scientists?

a. Scientists help humans do useful things, which makes the humans healthier, wealthier, etc., and governments often like to support health and wealth.

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

an atom

• How long did it take, or will take, for the dye to reach the trout stream?

few hours to days

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

o 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.

• 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 Cindicates another such mass of sand glued together by hard-water deposits .

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

• 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?

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

• 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?

o Cold from the change in Earth's orbit caused when the meteorite shoved the planet farther from the sun.

• Considering long-term averages, and assuming that we don't deploy space-based defenses against incoming meteorites, a reasonable estimate of the chance of an average U.S. citizen being killed by the effects of a meteorite or comet impact is that this risk is about the same as the chance of being killed by:

o Crash of a commercial airplane

• When considering the land surface:

o Deposition of sediments occurs in only a few places, with erosion or nondeposition occurring in most places to produce unconformities, and one must piece together geologic history from rocks in many places.

• 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:

o Global sea level is rising, covering more land.

• The Mississippi River:

o Has built a delta, which is several miles thick at its thickest point, from near St. Louis, MO to the Gulf of Mexico over millions of years.

• 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?

o High concentrations of silica found in the layer

• The Precambrian:

o Is the age of algae, and occurred just before the Paleozoic.

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

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

• We saw when we studied weathering that physical weathering makes little pieces from big, and that chemical weathering dissolves some things and makes other chunks. The different chemicals went into different places, dissolved or in chunks. When geologists classify sedimentary rocks, the first divisions are based on:

o Origin—rocks made from pre-existing pieces are separated from rocks made from precipitation of dissolved things.

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

o Precambrian, Paleozoic, Mesozoic, Cenozoic.

• 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:

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

• Which of these is an important idea that geologists use in learning which clastic sedimentary rocks are older, which younger, and what has happened to those rocks?

o Sedimentary layers start our nearly horizontal.

• Geologically speaking, the water table:

o Separates the water-filled region below the Earth's surface from the region closer to the surface in which some air exists in the spaces.

• The size of a typical sandy beach, averaged over a few decades, is usually controlled by:

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

• The river "wants" to leave this delta, and flow somewhere else, far to the west of the area covered by this map. Why?

o 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 above Landsat image from NASA shows Cape Cod, Massachusetts. This is a pile of sand and gravel out in the north Atlantic. The Cape has no large rivers, and is not especially close to any large rivers (the Connecticut and the Hudson are far out of the picture to the left). Looking along the far right-hand side of the Cape, the long white line is sand of the great outer beach (pink arrow), and sand deposits are prominent to the north and south (yellow arrows). What is going on?

o The ocean is eroding the outer beach, and the yellow-arrow ends are growing more slowly, so the Cape as a whole is shrinking.

• The picture above shows an outcrop along Interstate 70 in Utah. The green arrow points to a person, for scale. The pink arrows point to the ends of an interesting surface. Some rocks are below this surface, and other rocks above it. What happened to make this outcrop?

o The rocks below were deposited, hardened, turned on end, eroded to make an unconformity with a soil developing on top, and then other rocks were deposited on top of the soil.

• 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:

o 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.

• Large rivers sometimes have natural levees because:

o Water slows and deposits sediment as the water leaves the main river channel during floods.

• Can a good geologist ever find a material that is somewhere between sedimentary rock and metamorphic rock?

o Yes, because squeezing and heating sedimentary rock makes metamorphic rock, and intermediates exist.

• 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

o 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.

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

An unconformity is

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

Sediment is changed to sedimentary rock by:

• Cementation by hard-water deposits, intergrowth of new minerals, and squeezing under the weight of additional sediment.

If you went swimming in the single channel on this river, and grabbed sample of river bank, what would you likely come up with?

• Clay, that sticks together and can hold up steep slopes

Given the materials presented in class about the formation of caves, it is likely that most large caved are formed

• In limestone in moist climates

The above picture is from the Escalante-Grand Staircase National Monument. The pink arrows point along some interesting features. What are they?

• Joints, formed when the sedimentary rocks were broken by physical-weathering or other processes.

In the map, blue shows the MI river and the Gulf of Mexico, around the Birdfoot Delta of the river. Orange and red both indicate change in one direction and yellow and green indicate change in the other direction

• Orange is loss of wetlands over time, green is gain

What happened in this picture

• Rivers have delivered sediment to the sea, forming deltas that built up as they built out so that they still slope slightly downhill toward the sea

The "Law" of Faunal Succession:

• Was developed by an engineering geologist to aid in construction projects.

In the picture, Dr Alley is discussing events that are happening outside of Grand Canyon National Park, which may impact the park. What the issues?

• Water pumped out of the ground for gold courses and other uses evaporates so less water flows thru the ground to springs of the canyon