Geosc 10 rock ons

The Precambrian

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

What is accurate about the scientific theory of evolution today

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

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.

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

200

The extinction of many types of dinosaurs occurred about

65,000,000 years ago

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)?

A Just below the letter "A" there is a small unconformity. The layers below are cut along that surface. Layers must exist to be cut, so the lower layers are older, the upper layers are younger, and "up" was and is in the same direction, up in this picture.

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 bottom, flat on the top, rests on sand and gravel, and has sand dunes on top. In the lower picture, Dr. Alley is showing that the brown zone contains twigs and other organic material.What is the brown zone doing here?

A 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.

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

This rock in the picture above was modified by

A glacier, which scratched and polished the rock at A and plucked blocks loose at B, as the ice moved from A to B Indeed, ice sandpapers and striates the rocks it hits first, and then plucks blocks loose from the other side. And the striae go in the direction that the ice moved.

Look at the picture above. What happened here?

A great volcanic explosion occurred, spreading material across the landscape and leaving a hole. Nature has many ways to make holes, and many other ways to make mountains. Part of this class is learning to read the clues, just as geologists do. We saw at Death Valley that the faults tend to make straight lines. Streams on glaciers are not nearly this big, nor are river bends. And while George is cute, he could never dig such a hole. This is the aftermath of the eruption of Mt. St. Helens.

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

A huge amount, including whether the environment was land or water, whether it was warm enough for crocodiles or cold enough for ice, and much more

The ridge left behind by a glacier that outlines where the glacier had been is called

A moraine, composed of till (which is unsorted) and outwash (which is sorted).

Scientists often speak of consensus—the scientific community agrees that a particular theory is better than the competitors. What is such scientific consensus based on

A number of different experiments by different people that all had outcomes that were predicted accurately by the favored theory and not by the competitors

The picture above shows

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

The pink arrows point to a barrier beach, formed when waves fromthe ocean (on the left) washed away mud and piled up sand, after themud and sand were delivered by the stream flowing in from the upperright. The yellow arrows point to interesting features.How did they form?

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

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

A subduction-zone-type, steep andesitic stratovolcano This is Lassen Peak in Lassen Volcanic National Park, northern California. Lassen erupted between 1914 and 1921, near the south end of the Cascades chain of subduction-zone volcanoes, and was made a national park in 1916. Hot-spot volcanoes aren't as steep, plateau basalts cover state-sized areas with very flat-lying flows, cinder-cone volcanoes are much smaller, and George's piles are smaller yet.

An unconformity is

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

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.

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

We now know a lot about the big processes that shape the Earth's geology. Which of the following is NOT correct about that knowledge?

Almost all of the motion of lithospheric plates is vertical, with almost no horizontal motion.

Death Valley National Park preserves the lowest-elevation, hottest piece of the U.S. The park is fascinating for many reasons. What is accurate about volcanoes and Death Valley National Park?

Although no volcanoes are actively erupting at the moment this is being typed, eruptions have occurred in the geologically recent past (the most recent centuries or millennia), demonstrating the presence of hot rock at shallow depth beneath the valley.

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

An Appalachian-type or push-together obduction boundary

In the photo above, the letters A and B are in bowl-shaped features in east Greenland. If you were to walk along the ridge just below the yellow line, you would be balanced on a knife-edged ridge between the two bowls. That ridge is called:

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

In 2005, Hurricane Katrina brought a storm surge that overtopped the levees and flooded New Orleans, causing over 1400 deaths and perhaps $100 billion in damages. This flooding of New Orleans from a big storm was

An event that scientists had warned about for decades, based on the known size of hurricanes, and the sinking of the city and the Delta.

National Parks are

An invention of the United States that has spread around much of the world, as a way of protecting some of the finest parts of the world

If you get some of the right sort of organic material, and heat it in the right sort of way, perhaps with a little squeezing, you will end up with 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

When geologists consider sedimentary rocks, those rocks

Are classified first based on origin (clastic or chemical precipitate)

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

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

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

Because changes in the Earth's orbit have caused changes in the amount of sunshine received during certain seasons at different places on Earth.

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

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

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.

Which is the correct age progression, from younger (first) to older (last)

B, F, E, D, C The package of sediments C, D, E, F is upside-down, as shown by the footprints and mud cracks, so C is oldest, and F the youngest of these. B is above the unconformity above all of C, D, E, and F, so is the youngest of these five

Which of the following is not expected very often near a "textbook" subduction zone (that is, near a subduction zone that is so perfect and free of confusing complications that you would use it in a textbook to teach students)?

Basaltic hot-spot volcanoes such as Hawaii

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

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

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

Both oil and coal are nonrenewable resources, and at current usage rates and prices similar to today, oil will run out in about a century and coal will run out in a few centuries

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

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

CO2 + H2O + energy → CH2O + O2

Sediment is changed to sedimentary rock by

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

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

Cenozoic, Mesozoic, Paleozoic, Precambrian

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

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

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

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

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

Among fossil fuels

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

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

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

A glacier flowing down the side of a mountain has come into balance with the climate. Then, a climate change occurs, so that melting exceeds snowfall on the glacier. The glacier will

Continue flowing down the mountain, but shrink until a new balance is reached or until the ice disappears (of course, it must quit flowing as it disappears!).

Heat is moved around by convection, conduction and radiation (and by lemmings carrying space heaters, if lemmings ever carry space heaters). Which statement is more nearly correct?

Convection moves heat efficiently through the soft, hot rocks of the Earth's mantle, but is not efficient at moving heat through the space between the Sun and the Earth

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

Crash of a commercial airplane

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

Either counting of annual layers or radiometric techniques if the deposit is young (less than about 100,000 years), and radiometric techniques if the deposit is old (more than about 100,000 years)

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.

Glaciers move by

Deformation within the ice, and sometimes sliding over materials beneath or deformation within materials beneath

To get gas from the Marcellus shale, drillers

Drill into and then along the shale, and then pump in high-pressure fluids to fracture the rock and release the gas

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

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

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

In the photo above, Dave and Kym are discussing a model of the Waterpocket Fold in Capitol Reef National Park. The Waterpocket probably formed in the same way as the Front Range of the Rockies. This involved

Especially warm sea floor in the subduction zone off the west coast rubbed along under western North America and squeezed or wrinkled the rocks, folding them (probably with a push-together fault somewhat deeper under the fold).

Which is younger

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

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

Evolution proceeds in the direction desired by members of a generation

Religion and science always disagree

False

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

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

Gains carbon dioxide (CO2) from the air and then gains more carbon dioxide in the soil, becoming more acidic.

The New Madrid Fault Zone in Missouri has had some surprisingly big earthquakes. A magneto-hydro-astronomer at a small university near the fault zone reports that the gravitational effects of the coming alignment of several planets, together with the weakening of the magnetic field, will cause a giant earthquake on the fault zone on Wednesday morning between 1 and 4 am. Based on materials covered so far in this class, you would be wise to

Get back to whatever you were doing and ignore the forecast; although there might be a very small effect of planetary gravity or magnetic fields on earthquakes, no one has ever demonstrated the ability to make such detailed forecasts accurately, and many such forecasts have proven to be wrong.

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

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 Mississippi River

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

The glacier shown above

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

Which statement is true about the physical conditions required for convection to occur?

Heating from below, which reduces density and causes a tendency for the heated material to rise.

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

The interactions at the edges of plates are very important. Which is NOT an interaction that is commonly observed all along the length of one of the edges where two plates meet?

Hot spot

Which is the oldest fault

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

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

During the most recent ice age

Ice from Canada advanced across the Great Lakes and into the northern states of the US, but not farther.

Early geologists did not have radiometric dating techniques, or long layer-counted histories. Instead, they followed William Smith in putting things in order, and then used uniformitarian calculations based on modern rates of processes and observed results of processes in the geologic record. These early geologists, using these techniques, found that the Earth

Is more than about one-hundred-million years old

What is accurate about peer review of scientific papers

It provides quality control by eliminating many mistakes

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

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

Just over the thickness of a sheet of paper

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.

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.

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

Medial moraines, rocks picked up from points where tributary glaciers flow together.

What sort of rock is pictured above?

Metamorphic; The rock separated into layers as it was cooked and squeezed deep in a mountain range.

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.

Bigger earthquakes occur less frequently, but a bigger quake releases more energy and does more damage. An interesting question to ask about earthquakes (and about almost anything else!) is whether the increase in energy release and damage done is larger or smaller than the decrease in frequency as one looks at bigger earthquakes. Asked a different way, is most of the damage done by the many little earthquakes or by the few big earthquakes?

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

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

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

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 time, 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

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

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

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

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

One or more of True, lucky, or close to being true (or cheating), but we can't tell which.

Suppose that the sun suddenly became a little brighter, which would warm the world a little. Over the next few hundred years, what would you expect to happen

Other things would change in the Earth system, and these feedbacks would amplify the warming from the sun a little and cause the Earth to end up somewhat warmer than before the sun changed

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

What is accurate about seismic waves moving through the Earth?

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

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

Packaging substandard mortgages into "securities" and trying to sell them to unsuspecting people

Many plants are hard to get along with. Imagine crashing pell-mell through a thicket of devil's club (pictured above),in coastal Alaska, to get away from a charging brown bear. The native people use devil's club for medicinal purposes.We now know that

Plant protection by thorns is supplemented by 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

Ignoring good manners, you start rooting around in the nucleus of a poor, unsuspecting atom, to see what is in there. What are you most likely to find

Protons, usually with some neutrons hanging around among the protons

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

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

The rocks in the above picture sit along the side of the Blue Ridge Parkway in Virginia. The layers started out horizontal, but now are vertical. What happened?

Push-together forces when Africa and Europe ran into the Americas bent the rocks, tipping these up on end.

What tectonic setting is primarily responsible for producing Crater Lake?

Push-together subduction

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

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

Fossil fuels are usually formed from

Remains of formerly living things buried by sediments in regions with little oxygen

People sometimes take machines out into deep water to "mine" sand, and bring it back to beaches. Dumping a lot of new sand on a beach usually causes

The beach to lose the new sand over the next year or years, as waves and currents move the sand back to deeper water

Geologically speaking, the water table

Rises during or soon after rainstorms as spaces fill up, and sinks during droughts as water drains away.

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

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

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

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

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

In the two pictures above, I and II, show traces of former life in rocks 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 higher in the cliffs of the Grand Canyon, and sample II is from much lower, nearer to 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

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.

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.

On average around the world

Sea level is rising, as warming causes ocean water to expand, and glaciers to melt.

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

How is sediment related to sedimentary rock

Sediment is gradually hardened to sedimentary rock by various processes, and the point where the name changes from sediment to sedimentary rock is somewhat arbitrary.

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.

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?

Sedimentary layers start our nearly horizontal.

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

Shells of creatures that lived in the ocean about 20,000 years ago indicate that the ocean water was especially isotopically light then.

What tectonic setting is primarily responsible for producing the great San Francisco earthquake and the San Andreas Fault?

Slide Past

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

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

In the picture above, the pink and yellow arrows in front of Dr. Alley point to two rather different deposits from an eruption of the Hawaiian Volcano Kilauea. As described in the class materials, these materials are:

Small pieces thrown through the air, and frozen "waterfalls" of lava that flowed quietly before freezing.

The stiff basaltic rocks of the sea floor are bent as they enter subduction zones. This means that:

Subduction zones produce sea-floor trenches, which may be filled with water or with sediment washed from nearby land

Beaches change as seasons progress. 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

What is accurate about the "Law" of Faunal Succession

The "Law" was developed from the observation that using geologic reasoning to put rocks in order from oldest to youngest also put the fossils in those rocks in order

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 the 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

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.

Which is younger

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

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

The action of mass wasting, as soil and rock collapses off of newly steep canyon walls initially carved out by water.

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

The biggest amount is re-evaporated, mostly through trees, and most of the remainder soaks into the ground and then flows through the ground to streams.

Which is not accurate about the Grand Canyon, in Arizona

The canyon is wider at the top and narrower at the bottom because the river was wider when the region was wetter, and has narrowed as deserts spread recently

What is the "Ring of Fire"?

The complex of volcanic arcs fed by subduction zones encircling the Pacific Ocean.

The map above shows the Birdfoot Delta of the Mississippi River, where it empties into the Gulf of Mexico. The river is shown in blue, as is the Gulf of Mexico. The river "wants" to leave this delta, and flow somewhere else, far to the west of the area covered by this map.Why?

The delta has built up as well as out, and that makes some other path to the Gulf steeper and shorter than the one now being taken, and during a flood the river tends to take that shorter path and cut a new channel.

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

The cartoon above illustrates a specific geologic process. In which of the additional images can the same geologic process be seen?

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

A glacier does flow "downhill". Which is correct about the hill?

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

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 less by a magnitude-7 quake than by a magnitude-8 quake.

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

The heat that had been stored during evaporation from the ocean and was released when clouds formed on the west side of the Sierra

Great Rock really is a great rock on Cape Cod, as shown by Dr. Alley's relatives for scale.The picture doesn't even show all of the rock above ground, and there is as much rock below ground as above. Great Rock sits well north along the Cape, just inland of Coast Guard Beach. Most of the Cape there is sand and gravel. So why is the rock there?

The ice carried the rock here—glaciers carry big as well as little rocks, and can leave big ones even if most of the material carried by the glacier is then sorted in outwash.

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

Which is accurate about the Earth?

The lithosphere normally breaks, and the asthenosphere normally flows.

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?

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.

It is almost always interesting to ask whether most of the "action" comes from the few, rare events, or the many common events. For earthquakes, we saw that most of the energy is released by the few, big events. For mass movement, averaged over the land surface and over thousands of years, which moves the most material

The many, small events (often lumped together as soil creep) move the most material

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.

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

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

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

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.

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

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

Stephanie and Topher are standing next to the Colorado River in the Grand Canyon.What can be said of the water here?

The river was naturally muddy, but has been made clear because most of the sediment is settling out in the reservoir behind the dam upstream.

The picture above shows an outcrop along Interstate 70 in Utah. The green arrow points to a person, for scale. The pink arrows pointto 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.

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.

If you could jump in a time machine and zoom back to when the Earth was only half its current age, you would probably find

The total area of continents then was smaller than now; continents have grown over time as material scraped off downgoing slabs of subduction zones has been added to the continents.

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

The tracks of the glaciers will be easy to see, although minor modification by streams, wind and mass movement will have started.

What probably happened in the above picture?

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

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.

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

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.

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.

Which is most accurate about tsunamis?

They are big waves caused by very rapid displacement of a lot of water, which may occur in response to an undersea landslide, earthquake, volcanic eruption, or other cause

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

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

Hot spots are important geological features. What is accurate about hot spots?

They are rising towers of hot rock, perhaps from as far down as the core-mantle boundary, bringing heat up to feed volcanoes.

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

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

One of the big problems faced by National Parks is that

They must allow people to enjoy things today, and preserve those things for the future, but achieving both of these is not easy

A dam is built on a river, forming a reservoir. Over time, this likely will cause the fields of some farmers along the river just upstream of the reservoir

To be buried by sediment.

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.

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

Much melting in the mantle occurs near subducting slabs primarily because:

Water taken down subduction zones lowers the melting temperature in and near the slabs

The picture above shows a region of hard rock about six inchesacross from the Grand Canyon.The shape and polish of the rock areinteresting.It is likely that the rock

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

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

Large rivers sometimes have natural levees because

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

The picture above shows ocean in the upper right, a beach, and land in the lower left. The red dashes trace the crest of a wave. Waves move perpendicular to their crests. What principle might be illustrated by the picture?

Waves go slower in shallower water

The yellow line lies along the contact between sandstone (on the left) and reddish mudstone (on the right). The red arrows point along a place where the sandstone continues into the mudstone. The four sides of the picture are labeled A, B, C and D. What is most likely correct about these rocks

When the rocks were deposited, side B was the highest (it was on top). This is a cliff in the Grand Canyon. The picture was taken and then turned on its side. Originally, the muds of side D were deposited on a floodplain, a mud crack formed and sand fell into it (the red arrows) as the sand-dune rocks of side B were deposited on top.

You are dating a lava flow by the potassium-argon system. However, the offspring in this system are leaking out of the minerals. Which is accurate

You will think that the lava flow is younger than it really is, but you will be able to detect the error by comparing concentrations of offspring from the edges and centers of grains

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