Assessment Introduction Geology is happening all around you

QUESTION

9/26/2015AssessmentIntroductionGeology is happening all around you, right now—and you’re paying through the nose for it. Nature breaks rocks, including the funny­looking human­made ones wecall 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 thedamage. 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 canoccur!). 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. Byunderstanding 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 howto 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 ofresults of geologic processes that happened recently, together with some background information. Then, we’ll ask you some questions. Note that if your friend justdid 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 whatisn’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 beready 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 asyou 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.Question 1: BlacktopsFirst, examine blacktop pictures 1­6. 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 inwhich 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 nearly­abandonedroad 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 lotmore 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 geologyworks, 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, PuddintownRoad. The cracks are especially common where thewheels drive.Blacktop #2: Crack in blacktop, bike trail. ThereBlacktop #3: Crack in blacktop, edge of Big Holloware no trees nearby, no heavy loads have beenroad. Cracks in the road are most commonly at thedriving on this, and there are very few other cracks edge, or under the wheel tracks.nearby.Blacktop #4: Crack in blacktop, Big Hollow Road.The road is slanted here, and the broken­up partmay be sliding downhill a little. Notice that thecracks are damp and plants are growing in somecracks. The township has patched this, at leasttwice, but is still losing.Blacktop #5: A small section of road offHouserville Road, no longer regularly used, butrather old for blacktop. Notice that to the upperright and left the blacktop is almost completelygone. Some cracks are damp here, too, with plantsgrowing in some.Blacktop #6: Abandoned blacktop driveway inHouserville. This is a little hard to even recognize asa driveway.Click on this link if you would like to see all of the blacktop pictures in a new window. Once you look at the pictures and read the correspondingtext, come back into ANGEL to answer questions one and two.1.https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B31/89/26/2015AssessmentBlacktop #1: Cracks in blacktop, PuddintownRoad. The cracks are especially common where thewheels drive.Blacktop #3: Crack in blacktop, edge of Big Hollow Blacktop #5: A small section of road offroad. Cracks in the road are most commonly at the Houserville Road, no longer regularly used, butedge, or under the wheel tracks.rather old for blacktop. Notice that to the upperright and left the blacktop is almost completelygone. Some cracks are damp here, too, with plantsgrowing in some.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 in­between, and 5 for a long time. A reasonable inference is:A) Damage accumulates with time, so that older blacktop is more broken up.B) Blacktop is self­healing, so the cracks that the workers made installing the blacktop later were filled in when the blacktop softened under the hot summersun.C) Damage accumulates with time, and these pictures prove that time is the only thing that affects the quality of blacktop.Question 2: BlacktopCompare pictures 1 and 2, showing a newer road with more cracks, and an older bicycle trail with fewer cracks.Blacktop #1: Cracks in blacktop, PuddintownRoad. The cracks are especially common where thewheels drive.2.Blacktop #2: Crack in blacktop, bike trail. Thereare no trees nearby, no heavy loads have beendriving on this, and there are very few other cracksnearby.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 onwhat you saw in question 1, is that:A) Bicycles spread oil on the trail that keeps it from cracking.B) Bicyclists concentrate all their weight on skinny tires, breaking the blacktop quickly.C) Bicyclists aren’t as heavy as cars, and the extra stress from heavier things tends to crack blacktop.Question 3: GravestonesNext, look at the gravestone pictures 1­6. We will call all of the stones granite, marble or sandstone (some of the marble ones are limestone or dolomite, and someof 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 andgranodiorite). These are in the same cemetery. We know enough about stone­carving history that all of the stones would have had similarly clear and deep datesinitially. We chose good­looking stones to show you, and for which we could get clear pictures of the date without showing names or anything that anyone mightnot 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 not­quite­so­oldmarble stones that are already hard to read, with sandstone in­between. Thus, you may accurately assume that these pictures show an old and a new granitegravestone, an old and a new marble gravestone, and an old sandstone gravestone (there were no new sandstone gravestones, and very new few marblegravestones; almost all are granite now).https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B32/89/26/2015AssessmentGravestone #1: Granite, 2010. The grass stuck tothe stone was thrown there by the lawn mower;ignore the grass (you’ll see some in other pictures,and should ignore it there, too), and notice that thecarving is clear and sharp.Gravestone #2: Granite, 1914. Notice that thecarving is still clear and sharp. Letters are oftenabout 1/8 inch (3 mm) deep.Gravestone #4: Marble, 1856? (the “18” on theleft and “6” on the right are evident; not positiveabout the “5”. Notice that the carving is almosttotally gone.Gravestone #5: Sandstone, 1843. The clarity ofGravestone #6: Sandstone, 1843. This is the samethe numbers is somewhere between the granite and stone as in gravestone picture #5. The stone isthe marble. But, check the next picture.splitting, something like sheets of paper on a tablet.The marble and granite did not show such splitting.Gravestone #3: Marble, 2002. Notice that thecarving is clear and sharp.Click on this link if you would like to see all of the gravestone pictures in a new window. Once you look at the pictures and read thecorresponding text, come back into ANGEL to answer questions three and four.3.Think about the numbers shown by these pictures, and about the text given above. The best hypothesis is that:A) 1914 was a bad year, and 1843 a good year.B) The different stones wear away at different rates, with granite slowest and marble fastest.C) The different stones wear away at different rates, with sandstone fastest, marble slowest, and granite in­between.Question 4: GravestonesLook at gravestone picture 6, and continue with gravestone pictures 7 through 9, reading the descriptions.Gravestone #6: Sandstone, 1843. This is thesame stone as in gravestone picture #5. The stoneis splitting, something like sheets of paper on atablet. The marble and granite did not show suchsplitting.Gravestone #7: This is an old granite stone.Notice that a chip is missing from the corner.https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B33/89/26/2015AssessmentGravestone #8: This is an old marble stone (1860, Gravestone #9: This is lichen growing on an oldwe believe, although hard to read the last digit).granite stone. Simply looking at this stone won’t tellNotice that a chip is missing from the corner.you what the lichen is doing, but we independentlyknow that lichens tend to take rocks apartchemically to get useful nutrients to use in growing.If we carefully removed the lichen, we would findthat the rock beneath has lost some chemicals andgained others, as compared to the rock that isn’tunder the lichen (we didn’t want to upset anyone byscraping away at the gravestone, so we ask you totake our word on this one). If you go back andlook, there are lichens of other types on all of theold stones. But, some of the numbers have beenworn away without lichens, so other mechanismsmust be active.Click here to see all nine(9) pictures of gravestones in a pop up window. Once you look at the pictures and read the corresponding text, comeback into ANGEL to answer question four.4.Erosion of the stones—loss of rock material—has been occurring. The pictures, and their captions, show that:A) Removal of chunks of rock, chemical action under lichens, and perhaps other mechanisms of bit­by­bit removal of rock material contribute to erosion.B) Bit­by­bit removal of rock material is the only mechanism of erosion.C) Chemical action under lichens, and breaking of chunks of rock at corners of stones, are unequivocally the only processes removing rock.Question 5: ChemicalsNext, 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’tlichens, 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, andespecially the marble, perhaps dissolving them in rainfall. The picture Chemical 1 shows and describes things that are related to concrete, which is in some wayschemically 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 acrack in the roof of a drainage tunnel under FoxHollow Road just north of Penn State’s BeaverStadium. Rainwater picks up carbon dioxide from theair, and possibly acid rain from coal­fired electricplants, making a weak acid. When the weak acidhits limestone, or marble, or cement, it dissolvessome of the rock chemically. This is how cavesform, and other changes happen. If the water thenevaporates, or loses some carbon dioxide back tothe air, a cave formation can be deposited. Thepicture shows a “cave formation” growing along acrack in the roof of the tunnel. Thus, chemicalprocesses can dissolve rock, and can also depositrock. The chemical composition of the caveformation is the same as clam shells and many othershells (calcium carbonate), which may suggest whateventually happens to these chemicals if they stay inthe water rather than being left behind as caveChemical #2: The blacktop on the bike path hassmall stones in it. This one contains a piece of ironpyrite, the gray pebble surrounded by the dark ringof rust near the center of the picture. Iron pyriteproduces acid mine drainage from some old stripmines and some other places, because it containssulfur (which eventually becomes sulfuric acid) aswell as iron (which here is becoming rust). The topof the iron­pyrite­bearing pebble is lower than thetops of the materials around it.Chemical #3: This is a “concretion”, a big ball thatformed in a layer of shale, and now sits outside ofthe Deike Building on Penn State’s University Parkcampus. This contains some pyrite, and the rustingof that pyrite is contributing to the break­up of theconcretion. Many rocks contain a little pyrite, andnature deals with it, but too much of it can causeenvironmental problems.https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B34/89/26/2015Assessmentformations.Click on this link if you would like to see all of the chemical pictures in a new window. Once you look at the pictures and read the correspondingtext, come back into ANGEL to answer question five.5.Based on what you have seen and read:A) Rocks are changed physically, but also chemically, and the chemical processes may prove to be diverse and complex, involving rusting, dissolving inrainwater, actions by lichens, and perhaps others.B) Rocks are changed physically, but there is also exactly one important chemical process, as rainwater dissolves marble.C) Most of the changes to rocks are physical, such as breaking off chunks.Question 6: CornersYou 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 #1: This is a curb in front of the PennStater. Notice that the corner has been chipped inseveral places (the light­colored places).Corner #2: This is the edge of Pastureview Roadon the University Park Campus. You can see in thecenter where chunks of blacktop have broken off ofthe pavement (which is on 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.Click on this link if you would like to see all of the corner pictures in a new window. Once you look at the pictures and read the correspondingtext, come back into ANGEL to answer question six.6.After looking at the images above and reading their captions, take a look at this cartoon drawing of a gravestone. The big “F” is in the middle of the face of thegravestone, and the big “C” points right to a corner of the graveston. The pictures show that the “C” is more likely to be knocked off than the “F”. Why?https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B35/89/26/2015AssessmentA) The C can be hit from more sides, and the C has fewer neighbors helping hold it in.B) The C is supported by neighbors on only one side, but the F is surrounded by neighbors helping hold it in.C) The C can be hit from two sides, and the F from only one side.Question 7: SlidingNext, peruse the pictures labeled Slide 1 through 6, because they talk about things sliding or rolling downhill, not because they are “slides”. Chipmunks andgroundhogs 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 beenpushing 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 #2: This is a groundhog hole, with a lot ofSlide #1: This is a chipmunk hole in the cemetery.loose dirt downhill below the hole (the brown stuff). Slide #3: The dirt from the groundhog hole in theNotice that the rocks and dirt that the chipmunk dugYou can see a blacktop road at the very bottom.previous picture is burying grass here; the big piecesup are almost all to the lower right of the hole,The next picture is of the bottom of the dirt that the have slid to the bottom.which is the downhill side.groundhog dug up and threw downhill.Slide #4: This old, lichen­covered wall is along thesame hill that the groundhog was digging in. Toguide your eye, we’ve drawn a line along the bottomof the wall. Notice the bulge. You may notice thatthe stones look less regular in the bulge, and thatthere are a few that are light­colored (end of theyellow arrow) because they lack lichens. The nextpicture is taken looking along the yellow arrow.Slide #5: We’re looking at the bulge from the otherside now, with the irregular, light­colored rocksvisible. The wall was pushed out, and eventuallyfailed, and someone has reconstructed the wall,rolling some of the rocks over in the process so thattheir non­lichen­colored sides are on top.Slide #6: The big orange “P” is a pillar of a freewaybridge over a bike trail. The pink line guides youreye along the edge of the loose rocks, which havebeen rolling out onto the bike trail on either side ofthe pillar but not so much right where the pillar is.Notice that the rocks cover a very steep slope. Inthe lower left, there are loose rocks under the plants(hard to see, but they’re there). Notice that therethe rocks aren’t rolling out into the bike path.Click on this link if you would like to see all of the slide pictures in a new window. Once you look at the pictures and readthe corresponding text, come back into ANGEL to answer question seven.7.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 correctlyinfer from looking at the pictures shown here are:A) 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 evenwith a grassy slope.B) Once you get grass or other plants growing on top, the downhill motion stops.C) The weight of grass tends to move slopes downhill faster, so there is more motion under grass than in bare­soil places.Question 8: WashNow, look at the four “Wash” pictures, showing evidence of running water washing loose material across human­built things. Note that these slopes are not verysteep, and generally not nearly as steep as in the “Slide” pictures.https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B36/89/26/2015AssessmentWash #1: A side bike path comes in from the leftat the bottom of the picture to meet the main bikepath. Cyclists cutting the corner short (notice thetracks in the mud just to the left of the arrow) arehelping keep the grass from covering the dirt justthere. You can see that there is a “plume” of dirtthat has washed away from this bare place as shownby the arrow, and heads downhill away from us,angling across the bike trail towards Slab Cabin Run,which is just out of the picture on the far right.Wash #2: The pile of dirt is used for maintenanceof the nearby baseball diamond at Spring CreekPark. Kids play on the pile, birds take dust baths onit when people aren’t around, and it is otherwisedisturbed. When rain falls, the water runs towardsthe camera, around the parking bumper and out intothe grass to the left. Notice the trail of dirt that thewater has washed with it.Wash #3: Rainwater running toward the cameraalong the side of the road has washed gravel fromthe shoulder into the grass on the right, and ontowards the camera across the driveway in theforeground. The Township pays people to addgravel occasionally, to prevent a major dropoffdeveloping that could cause cars to wreck if a wheeldropped off the edge.Wash #4: In the Penn State agricultural landsnorth of the Penn Stater, boards have been placedacross steeply sloping gravel roads to trap the looserocks washed by rainwater. The hill slopes towardsthe camera. Rocks have piled up against the “dam”on the far side as high as the top of the board, cleanwater flows over and has eroded a little on the nearside, creating the dropoff we see, as shown by thearrows. These “dams” work, but they are far fromperfect.Click on this link if you would like to see all of the wash pictures in a new window. Once you look at the pictures and read the correspondingtext, come back into ANGEL to answer question eight.8.In general, the pictures seem to indicate that:A) The mud moves mostly when it is raining, and the bare parts of the landscape that are not paved contribute most of the moving mud.B) The mud moves mostly when it is raining, and all parts of the landscape contribute mud equally.C) The mud moves mostly when it is raining, and the grass­covered or paved parts of the landscape contribute most of the moving mud.Question 9: TreesNext, look at the pictures of sidewalks and a bike trail near trees. We have seen that there are cracks unrelated to tree roots. But, the cracks in these pictures arerather clearly related to tree roots. A scientist seeing a crack near a tree makes the hypothesis that the tree’s roots caused it. But, for this to be science, you woulddo some hypothesis­testing. Is there really a root under the crack? Is the occurrence of cracks near tree roots purely coincidental, or are there more cracks neartrees than you’d expect based on the number of sidewalks, the number of cracks and the number of trees we see? Do we understand the mechanisms? Can treeroots generate enough “oomph” to do the job? This one is pretty obvious, but real science never stops there.https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B37/89/26/2015AssessmentTree #1: Cracks in sidewalk and curb around anelm tree on Burrowes at University Park.Tree #2: Cracks in sidewalk and curb around anelm tree on Burrowes at University Park.Tree #3: Cracks in bike path below Sunset Park,State College.Click on this link if you would like to see all of the tree pictures in a new window. Once you look at the pictures and read the corresponding text,come back into ANGEL to answer question nine.9.A scientist sees a crack near a tree. A scientist, doing real science, will assume that the tree caused the crack, call it science, and move on.A) TrueB) FalseQuestion 10: Office WallsFinally, consider this last picture of cracks in the wall of Dr. Alley’s office. Click on this link if you would like to see a larger image.10. Now consider the following statement: “At least we don’t need to worry about weather and landslides and downhill motion and all of those things attackingbuildings, because natural processes don’t bother buildings.A) TrueB) FalseSubmitSave and Continue Laterhttps://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B38/89/26/2015AssessmentIntroductionGeology is happening all around you, right now—and you’re paying through the nose for it. Nature breaks rocks, including the funny­looking human­made ones wecall 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 thedamage. 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 canoccur!). 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. Byunderstanding 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 howto 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 ofresults of geologic processes that happened recently, together with some background information. Then, we’ll ask you some questions. Note that if your friend justdid 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 whatisn’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 beready 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 asyou 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.Question 1: BlacktopsFirst, examine blacktop pictures 1­6. 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 inwhich 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 nearly­abandonedroad 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 lotmore 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 geologyworks, 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, PuddintownRoad. The cracks are especially common where thewheels drive.Blacktop #2: Crack in blacktop, bike trail. ThereBlacktop #3: Crack in blacktop, edge of Big Holloware no trees nearby, no heavy loads have beenroad. Cracks in the road are most commonly at thedriving on this, and there are very few other cracks edge, or under the wheel tracks.nearby.Blacktop #4: Crack in blacktop, Big Hollow Road.The road is slanted here, and the broken­up partmay be sliding downhill a little. Notice that thecracks are damp and plants are growing in somecracks. The township has patched this, at leasttwice, but is still losing.Blacktop #5: A small section of road offHouserville Road, no longer regularly used, butrather old for blacktop. Notice that to the upperright and left the blacktop is almost completelygone. Some cracks are damp here, too, with plantsgrowing in some.Blacktop #6: Abandoned blacktop driveway inHouserville. This is a little hard to even recognize asa driveway.Click on this link if you would like to see all of the blacktop pictures in a new window. Once you look at the pictures and read the correspondingtext, come back into ANGEL to answer questions one and two.1.https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B31/89/26/2015AssessmentBlacktop #1: Cracks in blacktop, PuddintownRoad. The cracks are especially common where thewheels drive.Blacktop #3: Crack in blacktop, edge of Big Hollow Blacktop #5: A small section of road offroad. Cracks in the road are most commonly at the Houserville Road, no longer regularly used, butedge, or under the wheel tracks.rather old for blacktop. Notice that to the upperright and left the blacktop is almost completelygone. Some cracks are damp here, too, with plantsgrowing in some.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 in­between, and 5 for a long time. A reasonable inference is:A) Damage accumulates with time, so that older blacktop is more broken up.B) Blacktop is self­healing, so the cracks that the workers made installing the blacktop later were filled in when the blacktop softened under the hot summersun.C) Damage accumulates with time, and these pictures prove that time is the only thing that affects the quality of blacktop.Question 2: BlacktopCompare pictures 1 and 2, showing a newer road with more cracks, and an older bicycle trail with fewer cracks.Blacktop #1: Cracks in blacktop, PuddintownRoad. The cracks are especially common where thewheels drive.2.Blacktop #2: Crack in blacktop, bike trail. Thereare no trees nearby, no heavy loads have beendriving on this, and there are very few other cracksnearby.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 onwhat you saw in question 1, is that:A) Bicycles spread oil on the trail that keeps it from cracking.B) Bicyclists concentrate all their weight on skinny tires, breaking the blacktop quickly.C) Bicyclists aren’t as heavy as cars, and the extra stress from heavier things tends to crack blacktop.Question 3: GravestonesNext, look at the gravestone pictures 1­6. We will call all of the stones granite, marble or sandstone (some of the marble ones are limestone or dolomite, and someof 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 andgranodiorite). These are in the same cemetery. We know enough about stone­carving history that all of the stones would have had similarly clear and deep datesinitially. We chose good­looking stones to show you, and for which we could get clear pictures of the date without showing names or anything that anyone mightnot 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 not­quite­so­oldmarble stones that are already hard to read, with sandstone in­between. Thus, you may accurately assume that these pictures show an old and a new granitegravestone, an old and a new marble gravestone, and an old sandstone gravestone (there were no new sandstone gravestones, and very new few marblegravestones; almost all are granite now).https://cms.psu.edu/Section/Assessment/Delivery/AssessmentAll.aspx?entryId=BAA9E80DE2D74E018E1C9A92813002B32/89/26/2015AssessmentGravestone #1: Granite, 2010. The grass stuck tothe stone

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