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Exercise #2...

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Exercise #2: Geology is All Around You Due Sep 27 at 11:59pm

Points 100

Questions 10

Available Sep 14 at 12am - Sep 27 at 11:59pm 14 days

Time Limit None

Instrucons Geology is happening all around you, right now—and you’re paying through the nose for it. Nature breaks rocks, including the funny-looking human-made ones we call roads. The typical US motorist spends almost $200 in gas taxes per year to repair roads, the truckers pay more, and we’re still not keeping up with the damage. Dr. Alley needs to keep trapping the groundhogs that burrow under his house, so they don’t undermine it and cause structural damage (which really can occur!). People do die in landslides. Soil washes off farmer’s fields, and the next year’s crop needs more expensive fertilizer to replace what was lost. By understanding what is happening, we can save money and lives. And, we can begin to comprehend the processes that shaped the planet. The assignment in Exercise 2 is for you to notice what is happening around you geologically. Look, see, and understand. Unfortunately, we haven’t figured out how to give you credit for looking, and we can’t tell whether you’re really looking in the right places. So, we’re going to take you on a tour, by showing you pictures of results of geologic processes that happened recently, together with some background information. Then, we’ll ask you some questions. Note that if your friend just did this exercise, they may have had questions that looked similar but had very different answers—there are different versions of a question about what is, or what isn’t, so copying what your friend did may give you a very bad grade. The material here is easy enough that you’re much better off doing it, and that way you’ll be ready because we’ll build on this later in the semester. You will only get one chance to submit this exercise so be sure to review your answers carefully before submission. You can, however, save your answers as long as you do not submit them first. Do not forget to hit the submit button when you are finished. This exercise will NOT automatically submit since there is no time limit (except to submit it by the due date shown on the calendar). This exercise will be graded automatically. So, let’s head off down the road. Or the bike path. All of these pictures were taken one day on Dr. Alley’s bicycle ride to Penn State’s University Park campus. Look at a print all of the pictures beginning the exercise.

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(https://www.e-education.psu.edu/geosc10/node/2002) before

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Attempt 1

10 minutes

100 out of 100

Score for this quiz: 100 out of 100 Submitted Sep 20 at 5:51pm This attempt took 10 minutes.

Direcons for Quesons 1 & 2 First, examine blacktop pictures 1-6. All six are “blacktop”, not concrete or brick or something else, and please assume that all of them were similar when new, blacktop is blacktop, and any differences you see have been caused by events since the blacktop was laid down. The pictures are in approximate order of the year in which the blacktop was installed, with the road 1 built most recently, the bike trail 2 older, the road 3 and 4 built before the bike trail, and the nearly-abandoned road 5 and the nearlyabandoned driveway 6 built before 3 and 4, probably with the driveway oldest. The roads 1, 3 and 4 are roads, so they are driven on a lot more than the driveway or the bike trail, but they’re not the main street through town. We’re going to make a few educated guesses about ways that geology works, based on what we see in these pictures, what we know about roads versus bike trails or driveways, and what we know about the world.

Blacktop #1: Cracks in Blacktop #2: Crack in blacktop, Puddintown blacktop, bike trail. Road. The cracks are There are no trees nearby, no heavy loads especially common where the wheels drive. have been driving on this, and there are very few other cracks nearby.

Blacktop #3: Crack in blacktop, edge of Big Hollow road. Cracks in the road are most commonly at the edge, or under the wheel tracks.

Blacktop #4: Crack in blacktop, Big Hollow Road. The road is slanted here, and the broken-up part may be sliding downhill a little. Notice that the cracks are damp and plants are growing in some cracks. The township has patched this, at least twice, but is still losing.

Blacktop #5: A small section of road off Houserville Road, no longer regularly used, but rather old for blacktop. Notice that to the upper right and left the blacktop is almost completely gone. Some cracks are damp here, too, with plants growing in some.

Blacktop #6: Abandoned blacktop driveway in Houserville. This is a little hard to even recognize as a driveway.

You can see all of the blacktop pictures (https://www.eeducation.psu.edu/geosc10/node/1917) in a new window if you prefer. Once you look at the pictures and read the corresponding text, come back into Canvas to answer questions one and two.

Question 1

10 / 10 pts

Compare pictures 1, 3, and 5. All are blacktop roads, in a similar place, that experienced similar traffic (except that after it fell apart, 5 is no longer used much), but 1 has not been around very long, 3 in-between, and 5 for a long time. A reasonable inference is:

Correct! Blacktop is like leftovers in the refrigerator—the older it is, the worse it is.

The recently laid blacktop looks pretty good, and the blacktop that was put down the longest time ago is barely recognizable as blacktop. You should not be surprised to learn that damage tends to accumulate with time as the blacktop breaks up.

Question 2

10 / 10 pts

Compare pictures 1 and 2, showing a newer road with more cracks, and an older bicycle trail with fewer cracks. A reasonable inference based on these, and on what you saw in question 1, is that:

Correct! Bicyclists aren’t as heavy as cars, and the extra stress from heavier things tends to crack blacktop.

You can break a brand new coffee mug by hitting it with a hammer. Damage tends to accumulate with time, but extra stress also causes damage to accumulate. The bicycle trail is not stressed as much as the road because bicycles are lighter than cars and trucks, so the blacktop on the bicycle trail can last longer than the blacktop on the road.

Direcons for Quesons 3 & 4 Next, look at the gravestone pictures 1-6. We will call all of the stones granite, marble or sandstone (some of the marble ones are limestone or dolomite, and some of the granite are granodiorite, but we’ll keep it simple, because the marble and limestone and dolomite are similar to each other, as are the granite and granodiorite). These are in the same cemetery. We know enough about stone-carving history that all of the stones would have had similarly clear and deep dates initially. We chose good-looking stones to show you, and for which we could get clear pictures of the date without showing names or anything that anyone might not want us to use in a geology class. If you walked around the cemetery, you would find even older granite stones that have clear dates, and notquite-so-old marble stones that are already hard to read, with sandstone in-between. Thus, you may accurately assume that these pictures show an old and a new granite gravestone, an old and a new marble gravestone, and an old sandstone gravestone (there were no new sandstone gravestones, and very new few marble gravestones; almost all are granite now).

Gravestone #1:

Gravestone #2:

Granite, 2010. The grass stuck to the

Granite, 1914. Notice that the carving is still

Gravestone #3: Marble, 2002. Notice

that the carving is clear stone was thrown there clear and sharp. Letters are often about and sharp. by the lawn mower; ignore the grass (you’ll 1/8 inch (3 mm) deep. see some in other pictures, and should ignore it there, too), and notice that the carving is clear and sharp.

Gravestone #4: Marble, 1856? (the “18” on the left and “6” on the right are evident; not positive about the “5”. Notice that the carving is almost totally gone.

Gravestone #5: Sandstone, 1843. The clarity of the numbers is somewhere between the granite and the marble. But, check the next picture.

Gravestone picture

Gravestone #7: This is an old granite stone. Notice that a chip is missing from the corner.

Gravestone #8: This is an old marble stone (1860, we believe, although hard to read the last digit). Notice that a chip is missing from the corner.

Gravestone #9: This is lichen growing on an old granite stone. Simply looking at this stone won’t tell you what the lichen is doing, but we independently know that lichens tend to take rocks apart chemically

#6: Sandstone, 1843. This is the same stone as in gravestone picture #5. The stone is splitting, something like sheets of paper on a tablet. The marble and granite did not show such splitting.

to get useful nutrients to use in growing. If we carefully removed the lichen, we would find that the rock beneath has lost some chemicals and gained others, as compared to the rock that isn’t under the lichen (we didn’t want to upset anyone by scraping away at the gravestone, so we ask you to take our word on this one). If you go back and look, there are lichens of other types on all of the old stones. But, some of the numbers have been worn away without lichens, so other mechanisms must be active. You can see all of the gravestone pictures (https://www.eeducation.psu.edu/geosc10/node/1918) in a new window if you prefer. Once you look at the pictures and read the corresponding text, come back into Canvas to answer questions one and two.

Question 3

10 / 10 pts

Based on the appearance of the numbers and the corresponding text in the first six pictures, it is mBased on the appearance of the numbers and the corresponding text in the first six pictures, it is most likely that:ost likely that:

Correct! The different stones wear away at different rates, with granite most resistant and marble least resistant.

Time and stress matter, but so does composition. People behave differently at different ages in their lives, and may change behavior as the stress level changes, but what you’re really made of does show through in the tough spots. For rocks, granite stands up to the weather better than marble does in a Pennsylvania graveyard.

Question 4

10 / 10 pts

Erosion of the stones—loss of rock material—has been occurring. The pictures, and their captions, show that:

Correct! There may be several mechanisms of erosion, including chemical action under lichens, breaking off of chunks, and bit-by-bit removal that isn’t occurring under lichens.

A gravestone is “attacked” in many ways—bumped by lawnmowers, cracked as ice grows in tiny cracks on a cold night, and attacked chemically.

Direcons for Queson 5 Next, look at pictures Chemical 1, 2 and 3, and read the captions. We noted in the previous question that evidence (which we haven’t actually shown you) demonstrates that lichens promote chemical alteration of rocks. But, the marble gravestone, in particular, seems to have worn away in places where there aren’t lichens, and there aren’t piles of little pieces of marble at the bottom of the stone. This might suggest that other chemical processes are attacking the rocks, and especially the marble, perhaps dissolving them in rainfall. The picture Chemical 1 shows and describes things that are related to concrete, which is in some ways chemically similar to marble. The pictures Chemical 2 and 3 show other evidence of chemical changes going on in other types of rocks.

Chemical #1: This rather strange picture shows a crack in the roof of a drainage tunnel under Fox Hollow Road just north of Penn State’s Beaver

Chemical #2: The blacktop on the bike path has small stones in it. This one contains a piece of iron pyrite, the gray pebble surrounded by the dark

Chemical #3: This is a “concretion”, a big ball that formed in a layer of shale, and now sits outside of the Deike Building on Penn State’s University Park

Stadium. Rainwater picks up carbon dioxide from the air, and possibly acid rain from coal-fired electric plants, making a weak acid. When the weak acid hits limestone, or marble, or cement, it dissolves some of the rock chemically. This is how caves form, and other changes happen. If the water then evaporates or loses some carbon dioxide back to the air, a cave formation can be deposited. The picture shows a “cave formation” growing along a crack in the roof of the tunnel. Thus, chemical processes can dissolve rock, and can also deposit rock. The chemical composition of the cave formation is the same as clam shells and many other shells (calcium carbonate), which may suggest what eventually happens to these chemicals if they stay in the water rather than being left behind as cave formations.

ring of rust near the center of the picture. Iron pyrite produces acid mine drainage from some old strip mines and some other places, because it contains sulfur (which eventually becomes sulfuric acid) as well as iron (which here is becoming rust). The top of the iron-pyritebearing pebble is lower than the tops of the materials around it.

campus. This contains some pyrite, and the rusting of that pyrite is contributing to the break-up of the concretion. Many rocks contain a little pyrite, and nature deals with it, but too much of it can cause environmental problems.

You can see all of the chemical pictures (https://www.eeducation.psu.edu/geosc10/node/1920) in a new window if you prefer. Once you look at the pictures and read the corresponding text, come back into Canvas to answer questions one and two.

Question 5

10 / 10 pts

The pictures and their descriptions give you many insights to the processes by which the environment acts on rocks. These insights likely include:

Correct! Rocks are changed physically, but also chemically, and the chemical processes may prove to be diverse and complex, involving rusting, dissolving in rainwater, actions by lichens, and perhaps others.

A gravestone doesn’t need to stand up to one physical or chemical process, but many physical and chemical processes. Chemically, rain is naturally slightly acidic, our coal-fired power plants increase the acidity, lichens make their own acids, and acid attacks rock, while oxygen and water rust the iron in some minerals, and much more. In the words of Dr. Suess, “There I was all completely surrounded by trouble...”

Direcons for Quesons 6 You saw back in gravestone pictures 7 and 8 that the gravestones typically lost chunks from corners rather than from the middle regions of faces. Pictures Corner #1 and Corner #2 show similar things, with chips missing from the corner of a curb, and from the edge of a road.

Corner #2: This is the edge of Pastureview Road on the Corner #1: This is a curb in front of the University Park Campus. You Penn Stater. Notice that the corner has can see in the center where chunks of blacktop have broken been chipped in several places (the off of the pavement (which is on light-colored places). your left).

Gravestone #7: This is an old granite stone. Notice that a chip is missing from the corner.

Gravestone #8: This is an old marble stone (1860, we believe, although hard to read the last digit). Notice that a chip is missing from the corner.

You can see all of the corner pictures (https://www.eeducation.psu.edu/geosc10/node/1923) in a new window if you prefer. Once you look at the pictures and read the corresponding text, come back into Canvas to answer questions one and two.

Question 6

10 / 10 pts

Based on what you know about the world, and what you can see in the pictures, the most likely explanation why corners lose more chips than faces is:

Correct! Pieces on corners can be hit from two sides, while the middle of a face can be hit from only one side; and, a piece on a corner isn’t supported by as many neighbors as a piece on a face.

Neighbors are useful in lots of ways. They can protect you from sneak attacks coming from behind or beside you, and hold you up in case you start to fall. Lose the guard and the support, and you’re more vulnerable. The same is true for erosion—something sticking out on a corner is more likely to get hit and less strongly held in place, and so is much more likely to break off.

Direcons for Quesons 7 Next, peruse the pictures labeled Slide 1 through 6, because they talk about things sliding or rolling downhill, not because they are “slides”. Chipmunks and groundhogs have loosened rock and soil that has slid downhill in the first three. The wall shown in the next two is holding back material that seems to have been pushing by itself—there is no sign of a groundhog or a backhoe pushing the wall out, just a fairly steep slope with plants growing on it, creeping or sliding downhill. The sixth picture was taken in a place where observation shows that kids like to climb the slope above the bike trail, which may help move the rocks downhill.

Slide #1: This is a chipmunk hole in the cemetery. Notice that the rocks and dirt that the chipmunk dug up are almost all to the lower right of the hole, which is the downhill side.

Slide #3: The dirt from the groundhog hole in the previous picture is burying grass here; the Slide #2: This is a groundhog hole, with a big pieces have slid to lot of loose dirt downhill the bottom. below the hole (the brown stuff). You can see a blacktop road at the very bottom. The next picture is of the bottom of the dirt that the groundhog dug up and threw downhill.

Slide #4: This old, lichen-covered wall is along the same hill that the groundhog was digging in. To guide your eye, we’ve drawn a line along the bottom of the wall. Notice the bulge. You may notice that the stones look less regular in the bulge, and that there are a few that are lightcolored (end of the yellow arrow) because they lack lichens. The next picture is taken

Slide #5: We’re looking at the bulge from the other side now, with the irregular, light-colored rocks visible. The wall was pushed out, and eventually failed, and someone has reconstructed the wall, rolling some of the rocks over in the process so that their non-lichen-colored sides are on top.

looking along the yellow arrow.

You can see all of the slide pictures

Slide #6: The big orange “P” is a pillar of a freeway bridge over a bike trail. The pink line guides your eye along the edge of the loose rocks, which have been rolling out onto the bike trail on either side of the pillar but not so much right where the pillar is. Notice that the rocks cover a very steep slope. In the lower left, there are loose rocks under the plants (hard to see, but they’re there). Notice that there the rocks aren’t rolling out into the bike path.

(https://www.e-

education.psu.edu/geosc10/node/1919) in a new window if you prefer. Once

you look at the pictures and read the corresponding text, come back into Canvas to answer questions one and two.

Question 7

10 / 10 pts

Loose material can move downhill as it is pulled by gravity, eventually changing how steep slopes are and causing other changes. Some things you can correctly infer from looking at the pictures shown here are:

Correct! Grass or other plants growing on top tend to reduce the downhill motion, but the slow bulging of the wall suggests that downhill motion can occur ev...