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Whitbeck, R. H., 1871-1939 (Ray Hughes) / The geography of the Fox-Winnebago valley
(1915)
Chapter II. The origin and physical features of the Fox-Winnebago Valley, pp. 7-12
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THE ORIGIN AND PHYSICAL FEATURES 7 CHAPTER II THE ORIGIN AND PHYSICAL FEATURES OF THE FOX-WINNEBAGO VALLEY How THE ROCKS OF THE VALLEY WERE MADE In very remote ages-to be reckoned in millions of years-a broad, shallow sea extended into the very heart of the present continent of North America. North of this sea lay an ancient land-mass which makes up a large part of what is now Canada, and from which a shield-shaped portion projected southward. Part of that shield of ancient rock now forms northern Wisconsin. During this period, much (if not all) of Wisconsin was covered by the sea. From the old land-mass at the north, the streams eroded rock waste and carried it to the ocean, as streams are now doing. This rock-waste was spread upon the bottom of the adjacent sea and slowly built up layers of sediment, which in time became beds of sandstone, made of sand; beds of shale, made of clay; and beds of limestone, made of limey matter which settled from the sea-water or accumulated from the skeletons of corals and other. lime-using creatures. In this way the old shield became enclosed on three sides by beds of sediments which accumulated in the sea around it, and which lapped over one another like shingles. The layers which were deposited first rest upon the seaward part of the shield, while those next deposited rest upon the ones laid down first, the third upon the second, and so on. THE UPLirr OF THE ROCKS All of these layers of rock, together with the still older shield which was well-nigh buried under the sediments, were in a later period gradually uplifted into dry land. The sea slowly with- drew and land took its place. This uplift caused a gentle warping of the land now included in Wisconsin, so that the highest ground is in the northern part of the state, while the rock layers gently dip, or slope, toward the south, southeast, and southwest. I . -
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