John Wesley Powell, of the United States Geological Survey, and the leader of the first boat trip 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:, 1/1Correct Answer:, EYour Response:, E
, 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? , A., Precambrian metamorphic rocks with some igneous rocks intruded; the folding was caused by mountain-, Paleozoic sedimentary rocks that form the main walls of the canyon; the folding was caused by mass-movement processes before the rocks were hardened by hard-water deposits.C., Precambrian sedimentary rocks, preserved in blocks dropped down by Death-Valley-Type faulting; the folding was caused by the drag along the faults.D., Cement poured to make the walls of the new gift shop that sits above the canyon, painted to look like something more interesting.E., Recent lava flows from pull-apart faults near the west end of the canyon; the folding happened as the lava cascaded over the canyon walls and flowed toward the river.
12., The picture above shows a very hard piece of rock about six inches across, in the Grand Canyon. The surface of the rock looks rather different from the surfaces of many other rocks.What made this odd-looking surface? ,
- Fall '08
- Correct Answer, Points Earned