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The Heartland, Natural Features
Pleistocene Epoch, gentle slopes, Ice Age, Mississippi River, flatlands
Almost all of the Heartland is in the vast central lowland of North America. The land is mostly level with some gently rolling hills. Horizontal sedimentary strata of limestone, sandstone, shale, and dolomite underlie the entire region. The gentle slopes of the region result mainly from glacial action during the Pleistocene Epoch (1.6 million to 10,000 years ago). The flatlands and productive soils were produced during the last Ice Age at the close of the Pleistocene Epoch, as were the Great Lakes, which were formed by glacial scouring and then filled with the melt water of retreating glaciers. Almost all of the surface water in the Heartland drains into the river systems that feed the Mississippi River, and flooding is a natural hazard in the spring. Both the Great Lakes and the Mississippi have long served as vital transportation links that contribute to the economy of the region.
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