Aerial photo of Horseshoe Lake, an abandoned Mississippi River channel.
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Aerial photo of Horseshoe Lake, an abandoned Mississippi River channel.
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Although often very slight, differences in topography have a profound effect on soils, drainage characteristics, and thus the kinds and distribution of plants and animals that live in the American Bottom. This changing physical environment, with its ever-changing mosaic of wet and dry land, is largely responsible for the biological diversity of the American Bottom. In a short traverse from the top of a slightly elevated ridge down into a swale, to a stream's edge, and into a stream or slough one can encounter everything from a prairie, to a bottomland oak-hickory forest, to a freshwater stream habitat, to a wetland prairie, to a vegetation-choked slough. |
It is important to understand that the deposits of this late Pleistocene American Bottom canvas, later modified during the Holocene Period, accumulated and eroded in response to worldwide climate-driven geological processes and events. Thus, the Mississippi River valley and its floodplains, including the American Bottom, contain detailed records of these major geological and climatic events. The complexity of these features is staggering and considerable work is needed to develop a better understanding of the geomorphic history of the Mississippi River valley and their relation to worldwide climatic trends.