Rainwater Basin

The Rainwater Basin is a 4,200 mi.2 (10,900 km2) region of shallow lakes, marshes and other wetlands located south of the Platte River in south-central Nebraska. In the spring and fall months, millions of migratory birds pass through the region to feed and rest. The Rainwater Basin, along with the Platte River, is a major component of the Central Flyway of North America. These oval basins occur south of the Platte River on the loess-covered landscape of Nebraska.

The Rainwater basins are the surface expression of elliptical depressions developed in fluvial sands and gravels buried by a blanket of several meter-thick loess. These basins are palimpsest landforms created by the draping of a younger loess blanket over these underlying depressions (Zanner and Kuzila 2001). The loess, which overlies these features, contains an intact sequence, from bottom to top, of Middle Wisconsinan Gilman Canyon Formation, Late Wisconsin Peoria Loess, Brady Soil, Holocene Bignell loess resting upon a Late Illinoian Sangamon Soil developed in the fluvial sand and gravels in which these depressions have developed The intact layering of these different loesses and associated paleosols, which are each called “soil” by Zanner et al. (2007), prove that the loess has not been disturbed since it started accumulating over 27,000 years ago. Thus, these buried elliptical depressions are over 27,000 years old