February 1, 2012

Middle Mississippi River Border Division

The 8th Natural Division on the map is the Middle Mississippi River Border Division.(map)

The narrow band of river bluffs and rugged terrain along the Mississippi River floodplain from Rock Island County to St. Clair County and the lower Illinois River valleys make up this division. Bedrock cliffs and outcrops of limestone and sandstone are common along the river bluffs. Hill prairies occur atop south and west-facing bluffs, while oak-hickory forests predominate in the ravines and on cooler, north- and east-facing slopes. Deep deposits of loess (windblown silt) form high bluffs. Two peaks in Pere Marquette State Park are examples of loess deposits—McAdams Peak and Lovers Leap. The division is divided into two sections— Glaciated and Driftless. The topography of the Glaciated Section is a result of the Pleistocene glaciers—the Illinoian and pre-Illinoian stages. Unusual habitats found here include limestone glades, loess hill prairies, and glacial-drift hill prairies. The topography of the Driftless Section is rougher because the area escaped the glaciers. Limestone and sandstone outcrops frequently occur. Unusual habitats found here include limestone glades and loess hill prairies. Pere Marquette State Park is found in this section.

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