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1 | |
The energy source of erosional processes is the sun. Where does the energy involved in tectonic activity come from? |
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2 | |
List all the evidence you can for each of the following statements:
a. Granite is an igneous rock.
b. Mica schist is a rock that has been subjected to nonuniform pressure.
c. Compressional forces exist in the earth's crust.
d. Tectonic movement is going on at present. |
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3 | |
What landscape features are associated with faults? |
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4 | |
When stream erosion has been active for a long time in a region underlain by folded strata, what determines the position of the ridges and valleys? |
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5 | |
What geologic process is chiefly responsible for the landscape of a mountain range? |
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6 | |
Why is it believed that the region where the Rocky Mountains now stand was once near or below sea level? |
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7 | |
(a) What is the difference between the earth's crust and its lithosphere? (b) How is it possible for a plastic asthenosphere to occur between a rigid lithosphere and a rigid mantle? (c) If the asthenosphere is plastic, how can transverse seismic waves travel through it? |
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8 | |
When continental drift was first proposed three-quarters of a century ago, it was assumed that the continents move through soft ocean floors. Why is this hypothesis no longer considered valid? How does continental drift actually occur? |
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9 | |
How do the ages of the ocean floors compare with the ages of continental rocks? What is the reason for the difference, if any? |
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10 | |
What kind of biological evidence supports the notion that all the continents were once part of a single supercontinent? What kind of climatological evidence supports the concept of continental drift? |
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11 | |
The eastern coast of South America is a good fit against the western coast of Africa. What sort of evidence would you look for to confirm that the two continents were once part of the same landmass? |
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12 | |
Which is denser, the granitic rock of the continents or the basaltic rock of the ocean floors? Which extends deeper into the crust, the continents or the ocean floors? |
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13 | |
What body of water separated the ancient supercontinents of Laurasia and Gondwana? Are there any remnants of this body of water in existence today? If so, what are they? |
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14 | |
What mountain ranges of today were once part of the Tethys Sea? What kind of evidence indicates that the region where these mountains are was once below sea level? |
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15 | |
North America, Greenland, and Eurasia fit quite well together in reconstructing Laurasia, but there is no space available for Iceland. Why is the omission of Iceland from Laurasia reasonable? |
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16 | |
How does the origin of the Himalayas differ from that of the oceanic mountains that constitute the Mid-Atlantic Ridge? |
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17 | |
Which are younger, the Rocky Mountains or the Himalayas? |
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18 | |
Is the Atlantic Ocean becoming narrower or wider? The Pacific Ocean? |
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19 | |
The San Andreas Fault in California is a strike-slip fault that lies along the boundary between the Pacific and American plates. What does this indicate about the nature of the boundary? |
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20 | |
What happens at a subduction zone? |
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21 | |
The Andes are a young, still-growing mountain range on the west coast of South America. Why is there no similar mountain range on the east coast of South America? |
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22 | |
The distance between the continental shelves of the eastern coast of Greenland and the western coast of Norway is about 1300 km. If Greenland separated from Norway 65 million years ago and their respective plates have been moving apart ever since at the same rate, find the average speed of each plate. |
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23 | |
The oldest sediments found on the floor of the South Atlantic Ocean, which are 1300 km west of the axis of the Mid-Atlantic Ridge, were deposited about 70 million years ago. What rate of plate movement does this finding suggest? |
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24 | |
In Fig. 15-28, beds A to F consist of sedimentary rocks formed from marine deposits and rocks G and H are granite. What sequence of events must have occurred in this region? |
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25 | |
(a) What is an unconformity? (b) If one is shown in Fig. 15-28, where is it? |
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26 | |
What is a fault? If one is shown in Fig. 15-28, where is it? |
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27 | |
What is the basis of the radiocarbon dating procedure? |
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28 | |
The half-life of rubidium 87 is 47 billion years, and that of potassium 40 is 1.3 billion years. Would you expect the rubidium-strontium or potassium-argon method of radiometric dating to be more generally useful? Why? |
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29 | |
List as many different kinds of fossils as you can. |
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30 | |
Why are fossils still useful in dating rock formations despite the development of radioactive methods? |
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31 | |
Why are fossils never found in igneous rocks and only rarely in metamorphic rocks? |
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32 | |
Why are most fossils found in beds that were once the floors of shallow seas? |
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33 | |
What is the oldest division of geologic time? In what division are we living today? |
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34 | |
During what divisions of geologic time have living things existed on the earth? |
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35 | |
The earth's history is sometimes divided into two eons, Cryptozoic ("hidden life") and Phanerozoic ("visible life"), with the first corresponding to Precambrian time and the second extending from the beginning of the Paleozoic Era to the present day. What do you think is the reason for this division? |
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36 | |
The early atmosphere of the earth probably consisted of carbon dioxide, water vapor, and nitrogen, with little free oxygen. What is believed to be the source of oxygen in the present-day atmosphere? What bearing has this question on the relatively rapid development of varied and complex forms of life that marks the start of the Paleozoic Era? |
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37 | |
Precambrian rocks include sedimentary, igneous, and metamorphic varieties. What does this suggest about the geologic activity in Precambrian time? |
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38 | |
Precambrian rocks are exposed over a large part of eastern Canada. What does this suggest about the geologic history of this region since the end of Precambrian time? |
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39 | |
What conspicuous difference is there between Precambrian sedimentary rocks and those of later eras? |
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40 | |
What are the chief kinds of organisms that have left traces in Precambrian sedimentary rocks? |
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41 | |
Paleozoic sedimentary rocks derived from marine deposits are widely distributed in all the continents. What does this indicate about the height of the continents relative to sea level in the Paleozoic Era? |
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42 | |
Why is it believed that large parts of the United States were once covered by shallow seas? |
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43 | |
About 200 million years ago today's continents were all part of the supercontinent Pangaea. During what geologic era did Pangaea break apart into Laurasia and Gondwana? During what era did Laurasia break up into North America, Greenland, and Eurasia? |
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44 | |
Under what circumstances is coal formed? |
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45 | |
What is believed to be the origin of petroleum? of natural gas? |
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46 | |
What is the basis for the division of geologic time into eras and periods? |
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47 | |
What kind of animals were the dinosaurs? Were they mostly small, mostly large, or were they of all sizes? |
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48 | |
What is believed to be the reason for the disappearance of the dinosaurs? What is the evidence for this belief? |
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49 | |
During what geologic era did birds develop? From what type of animal did they evolve? |
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50 | |
What are some of the chief differences between reptiles and mammals? |
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51 | |
The same reptiles were present on all continents during the Mesozoic Era, but the mammals of the Cenozoic Era are often different on different continents. Why? |
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52 | |
In rocks of what era or eras would you expect to find fossils of (a) horses; (b) ferns; (c) clams; (d) insects; (e) apes? |
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53 | |
What were the Ice Ages? When did they occur? |
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54 | |
Minnesota has a great many shallow lakes. How do you think they originated? |
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55 | |
The Scandinavian landmass has been rising since the end of the most recent ice advance; the current rate is about 1 cm/year. Can you think of any reason for this rise? |
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