10. Two yellow lines in the picture above have been drawn on the picture by the instructional team. These lines follow an interesting surface. This surface is: A.A great fault, where push-together action shoved the upper rocks over the lower ones. B.A great unconformity, with sedimentary rocks above resting on igneous and metamorphic rocks below. C.A great unconformity, with sedimentary rocks above resting on older sedimentary rocks below. D.A great unconformity, with sedimentary rocks above resting on younger sedimentary rocks below. E.A great fault, where pull-apart Death-Valley-type faulting dropped rocks so that they could be preserved from erosion and seen today. John Wesley Powell, of the United States Geological Survey, and the leader of the first boattrip through the Grand Canyon, called the feature marked by the yellow lines “The Great Unconformity”. It separates horizontal Paleozoic sedimentary rocks, above, from inclined Precambrian sedimentary rocks, below. Points Earned: 0/1 Correct Answer: C Your Response: D
11. The above photograph was taken in the Grand Canyon, and shows a cliff that is approximately 30 feet high. What are the rocks in the cliff?
Points Earned: 1/1 Correct Answer: C Your Response: C 12. The picture above shows a very hard piece of rock about six inches across, in the GrandCanyon. The surface of the rock looks rather different from the surfaces of many other rocks. What made this odd-looking surface?A. The wind, which has been primarily responsible for carrying away sand bars, and which sand-blasts rocks with the sand.B. A glacier; the high plateaus adjacent to the canyon had
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