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The Tippecanoe sequence was the cratonic sequence--that is, the marine transgression--that followed the Sauk sequence; it extended from roughly the Middle Ordovician to the Early Devonian. ==Sedimentary characteristics== After the regression of the Sauk Sea early in the Ordovician, the exposed craton for a time underwent vigorous erosion, due to being located in a tropical climate; indeed, at this point in the Phanerozoic the North American continent roughly straddled the equator.〔Monroe, James S., and Reed Wicander. ''The Changing Earth: Exploring Geology and Evolution'', 2nd ed. Belmont: West Publishing Company, 1997. ISBN 0-314-09577-2 pp. 533-4〕 The Tippecanoe transgression ended this period of erosion, beginning with the deposition of clean sandstones across the craton, followed by abundant carbonate deposition.〔Monroe and Wicander, pp. 534-5〕 In the east these carbonates gradually become shales, representing sediments eroded from highlands created in the Taconic orogeny.〔 The Tippecanoe sequence may have been the deepest of the Phanerozoic. At one point during the Silurian period, the Taconic highlands—which later became the Appalachian Mountains--were the only part of North America that was not submerged.〔Monroe and Wicander, p. 537〕 The massive evaporite deposits of the Michigan Basin were created during this period.〔Monroe and Wicander, pp. 537-8〕 The Tippecanoe sequence ended with a regression in the early Devonian, to be followed later by the Kaskaskia sequence. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tippecanoe sequence」の詳細全文を読む スポンサード リンク
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