Eolian Sediments in the Greater Platte River Basins, Great Plains

Science Center Objects

The Greater Platte River Basins occupies a large part of the Great Plains of central North America. It is a semiarid region and like most semiarid regions, experiences a wide range of variability in year-to-year precipitation. This makes the region's geomorphic systems highly sensitive to climate changes. Much of the Greater Platte River Basins is covered with eolian sediments (dune sand, sheet sand, and loess) that are stabilized mostly by vegetation. Reactivation of these deposits is a distinct possibility with shifts in the overall moisture balance, because stabilizing vegetation is dependent on precipitation. Effects of future reactivation of eolian sand or loess would be high and would affect grazing land, agricultural land, wildlife habitats, and infrastructure.

A Task of the Greater Platte River Basins and Northern Plains Geologic Framework Studies Project.

 

Objectives

One objective of this work is to understand the dynamics of sand dune formation and activity in the Greater Platte River Basins. A second objective is to infer past climates from loess (windblown silt) records and compare results with general circulation models; paleoclimate data are fundamental to understanding future climate change and its potential effect.

Parabolic dunes in Wray dune field, eastern Colorado

Parabolic dunes in Wray dune field, eastern Colorado.

Stratification in a parabolic dune, exposed in a quarry at Wray, Colorado

Stratification in a parabolic dune, exposed in a quarry at Wray, Colorado.

Bignell loess, Peoria loess, and Brady soil as seen in sand dune

Road cut exposure at Bignell Hill, Nebraska, of Holocene Bignell Loess overlying late Pleistocene Peoria Loess. The Brady Soil, developed in the uppermost part of the Peoria Loess, marks the contact between the two loess deposits.

Photo of bison track in dunefield sand

Bison track in parabolic dune sand, Wray dunefield, eastern Colorado. Bison tracks are also found in dune sand in the Nebraska Sand Hills.