. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography and Space Administration in collaboration with the Remote Sensing Laboratory of the University of Kansas. The K-band radar system that produced the images was built by the Westinghouse Electric Corporation. deposits closely resemble the ancient mi- ogeoclinal foldbelts of the Paleozoic era and earlier. For example, the modern sedimentary wedge is much like the one found in the folded Appalachians of Pennsylvania. Both wedges are charac- terized by &
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography and Space Administration in collaboration with the Remote Sensing Laboratory of the University of Kansas. The K-band radar system that produced the images was built by the Westinghouse Electric Corporation. deposits closely resemble the ancient mi- ogeoclinal foldbelts of the Paleozoic era and earlier. For example, the modern sedimentary wedge is much like the one found in the folded Appalachians of Pennsylvania. Both wedges are charac- terized by "thickening out," signifying that they grow steadily thicker toward the east before they abruptly terminate. If the foregoing analysis is correct, one must conclude that geosynclines are actively forming along many continental margins today: eugeoclines at the base of the continental slope and miogeo- clines capping the continental shelves. It remains to be shown, however, that the crustal shifting associated with plate tectonics can convert these sedimentary prisms into the mountainous foldbelts that make up the fabric of the conti- nents, mostly as ancient eroded moun- tain roots rather than as modern moun- tain belts. In order to examine this possi- bility we must first summarize some of the basic concepts of plate tectonics. rPhe approximately eight rigid but shifting plates into which the earth is currently divided are thought to be about 100 kilometers thick. Most of the plates support at least one massive con- tinental plateau, often referred to as a craton. We can visualize the ideal plate as being rectangular, although only the plate supporting the Indian craton ap- proaches this simple shape. Along one edge of a crustal plate there is a subduc- tion zone, usually marked by a trench, where the plate dives steeply into the earth's mantle, attaining a depth as great as 700 kilometers before being fully ab- sorbed into the mantle. On the opposite side of the plat
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