GEOSC 10 - Final Exam Review
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.
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.
Which is accurate about the history of the Grand Canyon:
- In the deepest part of the canyon, the river cuts through rocks formed by metamorphism of older sedimentary rocks in the heart of a mountain range.
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.
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.
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
The Precambrian:
- Is the age of algae, and occurred just before the Paleozoic.
In chemistry, the type of an atom (what element it is) is determined by:
- the number of protons it contains in its nucleus
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.
Convection occurs:
- Because hotter things are less dense and tend to rise
If central Pennsylvania had a really dry year, and received only one-third of our usual rainfall, we would be just dry enough to be a called a desert if such dry years stayed for a long time. How much rainfall per year would we be receiving per year then? (In an average year, Pennsylvania gets about the same amount of precipitation as the average for the world.)
- 1 foot
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.
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?
- 2 is upstream of the Glen Canyon Dam, and 1 is downstream of the dam.
(UNIT 7) Evidence that glaciers were much bigger about 20,000 years ago than they are now includes:
- 20,000-year-old deceased shallow-water corals occur in growth position far below the surface on the sides of oceanic islands.
The great extinction at the end of the Paleozoic Era that changed the living types on Earth and made way for the origin of dinosaurs during the Mesozoic Era occurred about:
- 225,000,000 years ago
Rising air expands and cools; sinking air is compressed and warms. Typically, the size of the temperature change is:
- 5 degrees F/1000 ft change in elevation if condensation or evaporation are not occurring; 3 degrees F/1000 ft change in elevation if condensation or evaporation are occurring
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
In the first picture, 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 bo"om, flat on the top, rests on sand and gravel, and has sand dunes on top. In the lower picture, Dr. Alley is showing that the brown zone contains twigs and other organic material. What is the brown zone doing here?
- A block of ice from the glacier fell into an outwash plain deposited by the glacier's meltwater streams, and the ice later melted to leave a lake, the lake filled with peat and other organic materials, and was later buried by sand dunes, with erosion of coastal bluffs now exposing the deposit.
The bowl-shaped feature in the foreground of the above photo is:
- A cirque, a bowl gnawed into a mountain at the head of a glacier.
Near Aaronsburg, PA, a company wanted to start a limestone quarry, and planned to pump lots of water out of the ground to make things fairly dry near the quarry so it wouldn't fill with water. Concern was raised—would this affect the nearby trout streams? So, a little harmless dye was placed in a sinkhole next to the proposed quarry, and a fire-engine pumper added a lot of water to the sinkhole. How long did it take, or will take, for the dye to reach the trout stream?
- A few hours to days
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 above picture shows:
- A glacier, which is generally flowing toward you, carrying rocks picked up from the ridges; the yellow arrow points up one of the stripes of rock, and you can follow the stripe to the ridge where the rocks started.
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.
Two yellow lines have been drawn on the picture by the instructional team. These lines follow an interesting surface, which separate flat-lying sedimentary rocks, on top, from slanting sedimentary rocks beneath. This surface is:
- A great unconformity, with sedimentary rocks above res!ng on older sedimentary rocks below.
Look at the picture above. What happened here?
- A great volcanic explosion occurred, spreading material across the landscape and leaving a hole.
The picture above shows an odd cave on Hawaii. How did it form?
- A lava flow solidified on the outside, and then the center drained out, leaving the space.
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
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.
The pink arrows point to a barrier beach, formed when waves fromthe ocean (on the left) washed away mud and piled up sand, after the mud 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.
An unconformity is:
- A time gap in a sequence of sedimentary rocks caused by a period of erosion or nondeposition.
The peer review process, in which scientists submit write-ups of their ideas and experiments to a set of colleagues who judge how good the ideas are before the ideas can be published, is:
- A useful and important, even if imperfect, mechanism of quality-control for the scientific literature
(UNIT 9) 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.
Carbon dioxide, CO2, is an important greenhouse gas. Greenhouse gases warm the Earth primarily by:
- Absorbing some of the infrared radiation emitted from the Earth
Which of the following was probably important in contributing to extinction of most species at the same time the dinosaurs became extinct?
- Acid rain, from sulfuric acid from the meteorite hitting sulfur-bearing rocks, and from nitric acid from the heat of the meteorite burning the air.
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.
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
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
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.
The picture above shows an outcrop along Interstate 70 in Utah. The green arrow points to a person, for scale. Between the pink arrows, there is an interesting surface. What is it?
- An unconformity, where erosion occurred before the rocks above were deposited.
The picture above shows:
- An upside-down dinosaur track.
Heating of some materials produces coal. The most-heated is the most valuable. In order, from the MOST-VALUABLE / MOST-HEATED (FIRST) to the least-valuable / least-heated (LAST), the coals (and material that gives coal) are:
- Anthracite, bituminous, lignite, peat
(UNIT 11) 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.
Tsunamis:
- Are caused by earthquakes, undersea volcanic eruptions, or anything else that displaces a lot of water in a hurry
Tsunamis:
- Are like tornadoes; they can be predicted with some accuracy seconds to hours before they strike in most cases, allowing quick warnings to save many lives
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.
The volcanoes on the island of Hawaii (and the Loihi seamount, a submerged volcano to the southwest of Hawaii):
- Are not located at a subduction zone or other plate boundary, but instead poke through a plate drifting over the Hawaiian hotspot
Continents:
- Are the "unsinkable" part of the solid Earth; although a little of a continent might go down, most continental material stays near the surface
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.
Regions with mountain glaciers that experience much surface melting in the summer typically are eroded:
- At a faster rate than regions with streams but no glaciers.
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.
In a glacier, the ice moves fastest:
- At the upper surface, where ice meets air.
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
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
Given the materials presented in this class about the formation of caves, it is likely that most large caves are formed:
- In limestone in moist climates
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.
The next four (4) questions refer to the diagram above. This diagram 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. Remember that footprints and mudcracks tell you whether rocks are right-side up or upside-down, so look for those. Also, if a layer is upside-down, so are the layers that are in the same sedimentary pile, until you hit an unconformity. So, if you have layers Q, R, S and T in one sedimentary pile beneath an unconformity, and then layer U above the unconformity, and you learn that Q is upside-down, so are R, S, and T, but you must look for more information to tell which way is up for U. Referring to the rocks you see here ...... Which is the correct age progression, from older (first) to younger (last)?
- C, D, E, F, B
Which formula most closely describes the process by which plants make more of themselves:
- CO2 + H2O + energy -> CH2O + O2
You watched online as Dr. Alley carved a sand canyon with his finger. Based on what you saw, and on what you know about slopes, stability, mass movement, etc., if a landslide happened someplace last week, you would tell the neighbors:
- Care is required; landslides are removing instabilities and moving things towards stability, but a second landslide, or a flood, or other problems are real possibilities.
Sediment is changed to sedimentary rock by:
- Cementation by hard-water deposits, intergrowth of new minerals, and squeezing under the weight of additional sediment.
During the most recent ice age:
- Central Pennsylvania was just beyond the edge of the Canadian ice.
If you went swimming in the single channel of this river, and grabbed a smaple of the river bank, what would you likely come up with?
- Clay, that sticks together and can hold up steep slopes
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.
Chemical weathering of a continental rock such as granite in a climate such as that of Pennsylvania or other places where a good bit of rain falls, produces:
- Clays and rust, that do not wash away easily, and soluble ions, that do wash away easily
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.
Among fossil fuels:
- Coal is made by heating of woody plant material, and oil is made by heating of algae
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, frmo 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
Heat transfer by conduction is:
- Efficient over short distances but inefficient over long distances
A common way in which Philadelphia-size or bigger bodies of rock that were heated and squeezed deep in a mountain range then end up at the surface of the Earth is:
- Erosion removes the overlying mountains, and the deeper rocks float to the surface
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)
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 probably happened to create the two rocks with the orange surfaces, seen in the center of the above picture from Greenland?
- Expansion from water freezing in the crack wedged the rock apart
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
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.
Which is older:
- Fault I
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.
Your job depends on you finding the best available information on a particular technical topic. Where should you concentrate your search if you want to do it right and keep your job?
- Find and study refereed scientific articles in learned journals
The jobs of geologists include:
- Finding valuable things in the Earth, warning about hazards, learning how the Earth works, and educating and entertaining people
In the picture above, the ice that modified the rock moved:
- From left to right, striating the surfaces the ice reached first and plucking blocks loose from the far sides of bumps.
A glacier almost always flows:
- From where the glacier's upper surface is high to where the glacier's upper surface is low.
As rain falls through air, the water typically:
- Gains carbon dioxide (CO2) from the air, becoming a weak acid
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.
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:
- Global sea level is rising, covering more land.
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.
The picture shows sand and gravel in the bottom of Death Valley, and layers of sand, gravel, or other loose things can be found across the entire floor of the valley. What happened here?
- Gravels are being carried down from the mountains and spread across the valley by rivers, after faulting dropped the valley relative to the mountains
Sandy beaches:
- Grow if sand supplied from rivers or from coastal erosion exceeds sand lost to deep water, and shrink if the sand supply is smaller than the sand loss.
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.
Volcanoes in Death Valley:
- Have erupted recently (within the last centuries or millennia), showing that hot rock occurs at shallow depth beneath the valley
(UNIT 3) Continents:
- Have grown in area over time primarily by addition of island arcs, seamounts and sediments scaped off subducting slabs
The law that established the National Parks gave them a hard job, because it required that they:
- Help people enjoy the parks today, but also save the parks for the future
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.
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 silica found in the layer.
Lithospheric plates move on the surface of the planet. Plates meet at long plate boundaries. The types of interactions at these boundaries are very important. Which is NOT an interaction type commonly observed along the length of one of these boundaries?
- Hot spot
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 pictures labeled I and II show fossils from a sediment core collected from the floor of the Atlantic ocean, east of South Carolina. The sediment has not been disturbed by landslides or mountain building or other processes. The pictures were taken by Brian Huber, of the Smithsonian Institution, using a scanning electron microscope. The two samples in the sediment core were separated by the unique layer marking the extinction that killed the dinosaurs. Which is correct?
- I is older than the unique layer, and thus sat below the unique layer in the sediment on the sea floor.
Which correctly gives the order of the faults, from oldest (first) to youngest (last):
- I, J, H
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.
You hear an astronomer on the evening news, pointing out a coming alignment of planets and predicting that the extra gravitational attraction is sure to trigger a huge earthquake in California during the few hours of alignment. Based on what has been covered in this class, a reasonable approach is to:
- Ignore it; although gravitational forces such as tides and planetary pulls might possibly exert a very small effect on earthquakes, no one has successfully predicted the where-and-when of earthquakes
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.
One way to treat a dying beach is to dig up sand somewhere and dump it on the beach. What is this likely to accomplish?
- It causes the beach to lose the new sand over the next year or years, as the extra sand is washed back to deep water by waves and currents.
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.
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.
Any region of limestone bedrock containing caves, sinkholes, springs, etc. is called:
- Karst
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.
Silica tends to polymerize in lavas and make them thick and lumpy. Ways to reduce polymeriza!on of silica in lava include:
- Making the lava very rich in water and carbon dioxide.
The above picture shows a region a bit under a foot across, in a cliff in Red Canyon, just west of Bryce Canyon National Park. The rocks in the picture are the same as the rocks at the bottom of the beautiful Bryce Formation, the pastel rocks in Bryce Canyon. The red arrows surround a very interesting, reddish clast. What is the geological interpretation of this picture?
- Many older rocks, some with interesting histories, were rounded in a river, then mixed with sand and glued together by hard-water deposits; the resulting rock layer was broken into pieces, which were rounded in a stream, mixed with other rocks and sand and glued together by hard-water deposits, and the resulting rock layer was raised out of the river, and eroded to yield the modern outcrop.
What is accurate about the scientific results learned by counting annual layers in ice cores?
- Many tests show that some ice cores have reliably preserved annual layers, and the longest record extends back more than 100,000 years.
What sort of rock is pictured above?
- Metamorphic; The rock separated into layers as it was cooked and squeezed deep in a mountain range
What sort of rock is the dark material very close to the pink granite that Dr. Alley is pointing to in the picture above?
- Metamorphic; The rock separated into layers as it was cooked and squeezed deep in a mountain range
A larger national park and a smaller national park, otherwise identical, are completely surrounded by cornfields and Walmart parking lots, and have been surrounded for a century. You count the number of species of trees in each park. You probably will find:
- More species in the larger park, because it can hold more individuals thus reducing the risk of extinction
Which is NOT part of our modern view of geology?
- Most mountain building occurs in the centers of lithospheric plates
During chemical weathering, sodium is released as dissolved ions and transported to the ocean, where:
- Most of it stays in the water for a while, making the water salty.
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
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 have you personally been alive?
- Much less than the thickness of a sheet of paper.
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
Soil is produced by weathering of rocks, and moved to streams by mass-movement. Our understanding of nature and humans shows:
- Naturally, soil thickness reaches an approximate balance, with soil production and loss about equal if averaged over an appropriate !me, but human activities have upset this balance and caused soil to thin.
The final arbitrator between two alternate theories (for example Aristotle's and Newton's ideas) is:
- Nature, and experiments conducted to test each idea
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.
Which of the following is NOT a scientifically accepted statement about the occurrence of transitional forms in the fossil record?
- No one has ever discovered a single fossil of any transitional form
Extinction of existing species:
- Occurred at a low level throughout geologic history, punctuated by mass extinctions when many types were killed over very short times.
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
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 of more of True, lucky, or close to being true (or cheating), but we can't tell which
What is accurate about the land surface today, that you can observe in places such as Pennsylvania?
- Sediment is being deposited in a few places, but most places are eroding.
In the map above, blue shows the Mississippi River, and the Gulf of Mexico, around the Birdfoot Delta of the river. The USGS image uses different colors to indicate changes in the delta. Orange and red both indicate change in one direction, whereas yellow and green indicate change in the other direction. Based on the material presented in this class:
- Orange and red indicate loss of wetlands over time, whereas yellow and green indicate gain of wetlands over time.
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
The pictures show famous volcanoes, that are 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 cartoon above illustrates a specific geologic process. Which of the additional geologic images DOES NOT feature this same process at work?
- Picture of mountain in the ocean surrounded by water
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 of 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 geologic time scale is, starting with the oldest and ending with the youngest:
- Precambrian, Paleozoic, Mesozoic, Cenozoic.
Nuclei of atoms are made up of:
- Protons, usually with neutrons added
(UNIT 2) The picture above shows a fault in a place where mountains come down near the coast. What likely happened to form the ramp (also called a scarp) behind the person?F
- Pull-apart forces pulled the rocks apart, making the break, and allowing one side to drop relative to the other
This is a photo of a road cut through a mountain called Sideling Hill, in Western Maryland. What happened here?
- Push-together forces when Africa and Europe ran into the Americas bent the rocks, which later were exposed at the surface by erosion
(UNIT 4) 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
What tectonic setting is primarily responsible for producing Crater Lake?
- Push-together subduction
(UNIT 10) 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.
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
Hot spots:
- Rise from as deep in the mantle as the core-mantle boundary to the surface of the Earth, bringing up heat and feeding volcanoes
Geologically speaking, the water table:
- Rises during or soon after rainstorms as spaces fill up, and sinks during droughts as water drains away
(UNIT 6) What happened in the picture above?
- 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
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
What is accurate about seismic waves moving through the Earth?
- S-waves (also called shear-waves) move through solids but not liquids
The two pictures above, I and II, show fossils inrocks from the Grand Canyon. Each is "typical"; the rocks near sample I contain fossils similar to those shown in sample I, and the rocks near sample 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.
Acadia is beautiful even in the rain and fog, but the park still doesn't have many sandy beaches, and this is surely not a sandy beach, the rocks are granite, broken off the granite bedrock. Why aren't there sandy beaches?
- Sand is produced or supplied slowly enough, and sand loss to deep water is fast enough, that sandy beaches do not form.
Sometimes, science and religion come into conflict. This is because:
- Science and religion can coexist just fine with a little effort, but sometimes choose not to do so.
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
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.
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.
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 dam is built on a river, forming a reservoir. Over time, this likely will cause:
- Sedimentation to bury farmer's fields upstream of the reservoir, and erosion of sand downstream of the dam
Geologic history involves learning the order of events in the past (which came first?), and, what happened. Part of "what happened" is reconstructing what the environment was like in the past. What is accurate about the human effort to learn about past environments?
- Sediments and sedimentary rocks provide much information about whether they were deposited in the ocean or on land, whether the climate was hot or cold and wet or dry, and more.
What was going on geologically that caused the earthquakes that knocked down much of San Francisco in 1906?
- Slide-past motion along a great fault
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.
Glaciers form where:
- Snowfall exceeds melting for a long enough time.
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.
What is accurate about sediments and sedimentary rocks and metamorphic rocks?
- Squeezing and heating can turn loose sediment into sedimentary rock, and sedimentary rock into metamorphic rock, with all the intermediate steps observed in nature.
Suppose that CO2 in the atmosphere was held at a constant, natural level for a few thousand years. Thenm 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
Geologists get to play with chemistry, physics, biology... and history! And what a history you will meet as you work your way through the course. Starting at the beginning, the textbook provides scientifically accepted start of the story... and promises that you'll get to explore some of the evidence for that scientific view, later in the semester. Meanwhile, which is more nearly correct of the scientifically accepted view?
- The Earth formed from the falling together of older materials, about 4.6 billion years ago
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
(UNIT 12) If we could artificially double the CO2 content of the atmosphere and then hold the CO2 content at that level for a thousand years, the most likely effect would be:
- The Earth would warm a few degrees, and then the temperature would stabilize at that new, warmer level.
The top picture from the coast of Greenland, and the bottom picture from Bear Meadows Natural Area in central Pennsylvania, are geologically related. How?
- The Greenland picture shows rocks that have been creeping downhill on permafrost, and Bear Meadows probably was formed when such a creeping mass dammed a stream during the ice age.
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 subduc!on 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.
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
What is the "Ring of Fire"?
- The complex of volcanic arcs fed by subduction zones encircling the Pacific Ocean.
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
The picture above illustrates what scientific principle?
- The equator is hotter than the pole because the sun hits the equator directly but the sun hits the pole a glancing blow
In the picture above, Dr. Alley is discussing events that are happening outside of Grand Canyon National Park, which may impact the park. What are the issues he is discussing?
- Water pumped out of the ground for golf courses and other uses evaporates, so less water flows through the ground to the springs of the canyon
Most of the material moved by volcanoes is from the few, big ones rathen than 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)
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.
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
Air that passes over the Sierra Nevada from the Redwoods to Death Valley is warmed by roughly 30 degrees F, even if the air goes over at night. Where does the energy come from?
- The heat that had been stored during evaporation from the ocean and was released when clouds formed on the west side of the Sierra
If you went to Greenland and drilled a hole in the ice sheet, then came back later and surveyed the hole, you would find that the shape of the hole had changed. If you asked Dr. Anandakrishnan why the shape changed, he would tell you that the ice sheet was flowing. He would be correct. What does he mean by this?
- The ice is not too much colder than its melting point, and deforms something like hot rocks in the mantle or a chocolate bar in your pocket.
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.
What is accurate about a typical volcano formed by erup!ons from a hot spot?
- The lava of the volcano is mostly basal!c in composi!on, with gradual sides where the volcano projects above sea level, but steeper sides on undersea portions.
What type of mass movement moves the most material, averaged over the Earth's land and over long times?
- The many, small events move the most material.
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 Na!onal Park. The picture above shows a hillslope that is about 1⁄2 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.
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.
Large rivers have many interes!ng features, including:
- The natural levees, formed when flood waters leaving the channel slow down and drop much of their load near the channel; beyond the natural levees is the flood plain, where much of the rest of the mud in a flood is deposited in a thin layer.
You are a famous scien!st, renowned for the well-accepted idea you developed over the last 15 years. A new idea suddenly appears from some upstart junior scientist. For the new idea to overthrow your well-accepted idea and gain widespread scientific acceptance, what must happen?
- The new idea must explain the things that your old idea explained, and do a better job than your old idea in predicting the outcomes of many new experiments designed by various people to test the ideas.
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 is atomospheric 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 contiue our current behavior
At Cade's Cove, in the Great Smoky Mountain National Park, there is an unusual arrangement of rocks where older rocks are sitting on top of younger rocks, though neither layer has been overturned. This is because:
- The older layer was thrust over the younger layer by the forces of obduction
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.
Earthquakes can be caused in many different ways. The best interpreta!on 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.
(UNIT 8) 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 por!on; 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.
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?
- 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.
Sea level can change locally for many reasons, but averaged over all of the oceans of the world:
- The seas are rising, because warming is causing the ocean water to expand and mountain glaciers to melt.
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.
One practical radioactive system used to date lava flows involves:
- The solid potassium-40, which decays to the gas argon-40.
Which is younger:
- The tree
Most landslides happen when:
- The unconsolidated materials on hillslopes are very wet and thus heavy and slippery, and the water doesn't have to "break" as the grains move.
The floor of Death Valley is about two miles lower than the mountain peaks around it. How did this happen?
- The valley floor has dropped by more than two miles relative to the mountains, but erosion has removed the mountain tops and the sediment produced has partially filled the valley, leaving an elevation difference of two miles
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.
(UNIT 5) What is accurate about the planet's climate system?
- The wind blows because heating near the equator drives convection cells in the atmosphere, and the winds appears to curve to the left or right over the surface of the planet because of friction produced by the spherical planet's rotation beneath the atmosphere
The age of rocks near a sea-floor spreading ridge can accurately be described as:
- The youngest rocks are near the ridge, and the rocks get progressively older as you go away from the ridge in both directions
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.
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
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
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.
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
The things that glaciers deposit include:
- Till (which is unsorted) and outwash (which is sorted).
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 see sedimentary rocks of western Pennsylvania to see bituminous, and to the metamorphic rocks of eastern Pennsylvania to see anthracite.
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)?
- Uniformitarian calculations show that the Earth is more than about 100 million years old, and radiometric techniques tell us how much older.
The picture above shows a muddy sandstone that was deposited on a flood plain. Dr. Alley's index finger in the lower left points along a ridge on the surface of the rock (shadows are to the lower right of Dr. Alley's finger and to the lower right of the feature he is poin!ng along; his finger is above the rock, so the feature must be a ridge and not a trough). The rock is:
- Upside-down; you are looking at the side that was facing down toward the center of the Earth when the rock was deposited.
The "Law" of Faunal Succession:
- Was developed by an engineering geologist to aid in construction projects.
In the photo above, the jetty (which is a big wall, and could also be called a groin) was constructed out from the coast in the state of Washington. The water is shallow very close to the jetty, and deeper as you move away to left, right, or off the end of the jetty at the lower right. Look at the pattern of waves, which tells you that:
- Waves go slower in shallower water.
The mountain range that contains the folded Appalachians, including Mt. Nittany near Penn State's University Park Campus, and the Great Smoky Mountains, was raised to high elevation primarily:
- When the proto-Atlantic ocean closed, at a push-together boundary
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 still-different, still-denser material, because the planet is made of concentric layers, sort of like an onion
Using ordinary means (fire, sunlight, our digestive systems) we can take matter apart into smaller and smaller pieces, and the smallest pieces we typically produce are:
- atoms
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
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
The cartoon above illustrates a specific geologic process. In which of the additional images can THE SAME process be seen?
- the pictire of the tan-brown and blue colorful rock with curved lines
(UNIT 1) What is an accurate description of the job of a scientist?
- the scientist invents new ideas, and goes on to show that some of those ideas are false
