1. Three lines of evidence in support of the crustal uplift concept are fossilized shells of marine invertebrates found in mountain regions, wave-cut terraces, and elevated clam borings.
2. The evidence that initially led geologists to conclude that mountains have deep crustal roots was found by plumb bobs. It was found that the thickest crust was found to be under the mountains.
3. When weight is added to a floating object the object subsides and when weight is subtracted the object uplifts. This principle applies to changes in the elevation of mountains by when deposition occurs on the mountain it subsides and when erosion occurs it uplifts. The term applied to the adjustment that causes crustal uplift of this type is isostatic adjustment. As erosion lowers the summits of mountains uplifting responds to the reduced load and when deposition occurs it subsides.
4. One line of evidence in support of the idea that the lithosphere tries to remain in isostic balance is Ice Age ice sheets. When continental glaciers occupied portions of North America during the Pleistocene Epoch, the added weight caused down warping in the Earth’s crust. In the 8,000-10,000 years since the last ice sheet melted, uplifting has occurred.
5. A mountain range that is believed to partly be supported by strong, thick lithosphere is the Himalayas.
6. An accretionary wedge is a large wedge-shaped mass of sediment that accumulate in subduction zones. Sediment is scraped from the subducting oceanic plate and accreted to the overriding crustal block. It is formed during the development of a volcanic arc where sediments are derived from the land and scraped from the subduction plate and plastered against the landward side of the trench.
7. A passive margin is the continental margin when it is not a plate boundary but a part of the same plate as the adjoining oceanic crust. An example is the east coast of the United States. An example of an active continental margin is the west coast of South America.
8 .The Sierra Nevada and the western Andes are similar by they both are exposed batholiths, due to erosion, composed of crystalline metamorphic and igneous rocks. The Western Andes is a remnant of original island arc and the Sierra Nevada is a remnant of a portion of a volcanic arc.
9. The discovery of a sliver of oceanic crust in a continental interior would tend to support the theory of plate tectonics. This moves away from the continental drift theory which proposed that the continents moved through, not with the ocean floor like the theory of plate tectonics. The lithosphere contains about twenty plates.
10. Geologists believe that the northward journey of India is near an end because numerous earthquake recorded off the southern coast of India indicate a new subduction zone may be in the making which would provide disposal for the floor of the Indian Ocean which is continually being produced at a spreading center.
11. The plate tectonics theory helps explain the existence of fossil marine life in rocks at the top of the Ural Mountains by the European continent collided with the Asian continent producing the Ural Mountains. When they collided the marine sediments were pushed upward.
12. According to the plate tectonics model a major mountain system forms by oceanic-oceanic convergence. Subduction of the ocean-side. Sediments and water melt together forming volcanic island arcs. Then the volcanic island arc is pushed onto the continent. Then oceanic-continental convergence occurs. Subduction then continues and a volcanic arc forms. Then continental-continental convergence occurs. Neither plate subducts because both plates are the same density. Volcanism now stops and earthquakes continue.
13. A terrane is any crustal fragment whose geologic history is distinct from that of adjoining terranes. The word terrain indicates the lay of the land.
14. On the basis of current knowledge, the major difference between the evolution of the Appalachian Mountains and the North American Cordillera is that the Appalachian Mountains resulted from a collision between North America, Europe, and Northern Africa. It formed from several distinct episodes of mountain building over a period of nearly 300 million years. The North American Cordillera formed by fragments migrated toward and collided with the west coast of North America over the past 200 million years. It is believed that many of the terranes found there were once scattered throughout the Eastern Pacific.
15. The formation of fault-block mountains results from mountain building that is associated with tensional stress. It is bounded on at least one side by high-to-moderate angle normal faults.
16. The forces of deformation associated with fault-block mountains to those of most other major mountain belts is that fault-block mountains are formed by tensional stresses while all the other mountain ranges are formed by compressional stresses.
17. The opposing views on the origin of the continental crust is that continental crust formed early in the Earth’s history and the crust originated during a primeval molten stage and coincided with the segregation of material that produced the Earth’s core and mantle. The opposing view says that the continents have grown larger through geologic time by the gradual accretion of material derived from the upper mantle.