Economic Geology of the United States; With Briefer Mention of Foreign Mineral Products (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER III. PHYSICAL GEOGRAPHY AND GEOLOGY OF THE UNITED STATES. There are five geographical zones in the United States: (1) the southern coastal plains; (2) the mountains of the eastern states; (3) the inland plains and plateaus of the central western and southern states; (4) the Lake Superior hilly region, a southern extension of the Canadian Highlands; (5) the Cordilleran region, including the Rockies, Sierra Nevadas, and Coast ranges, with their enclosed plateaus and basins. These are capable of much more minute subdivision, but this will serve as a general classification upon which to base the summary which follows. Coastal Plains. ? There are several distinct parts to this area, all of which, however, are marked by the possession of the general features of a plain extending inward from the coast line, and composed of recent strata. The Quaternary Coastal Plains, or coastal plains proper, a subdivision of this general region, are the most recent additions to this country; being, in fact, old sea-bottoms, so recently elevated above sea-level that in many places the fossils entombed in their strata are the same as the living species in the neighbouring ocean. The rocks here are horizontal, or nearly so, and consist of the usual materials formed along shore lines. Sandstones, clays, and conglomerates predominate, and while in some places the strata are partly or completely consolidated, for the most part they are still incoherent deposits.Their origin has been partly from the action of waves upon the old shore line, partly from river deposits assorted and distributed by the oceanic waves and currents. Just such a deposit is being formed near the shore in these same regions at present. The coastal plains, which exist in New Jersey as a narrow strip and are not fo...