200,000 years of climate change recorded in eolian sediments of the High Plains of eastern Colorado and western Nebraska

Loess and eolian sand cover vast areas of the western Great
Plains of Nebraska, Kansas and Colorado (Fig. 1). In recent
studies of Quaternary climate change, there has been a renewed
interest in loess and eolian sand. Much of the attention now
given to loess stems from new studies of long loess sequences
that contain detailed records of Quaternary glacial-interglacial
cycles, thought to be a terrestrial equivalent to the foraminiferal
oxygen isotope record in deep-sea sediments (Fig. 2). Loess is
also a direct record of atmospheric circulation, and identification
of loess paleowinds in the geologic record can test atmospheric
general circulation models. Until recently, eolian sand on
the Great Plains had received little attention from Quaternary
geologists. The past decade has seen a proliferation of studies of
Great Plains dune sands, and many studies, summarized below,
indicate that landscapes characterized by eolian sand have had
dynamic histories.

On this field trip, we will visit some key eolian sand and
loess localities in eastern Colorado and southwestern Nebraska
(Fig. 1). Stratigraphic studies at some of these localities have
been conducted for more than 50 years, but others have been
systematically studied only in the past few years. Many of the
data which appear in this guidebook have been derived from
previous studies (Swinehart and Diffendal, 1990; Madole,
1994; Loope and others, 1995; Maat and Johnson, 1996; Muhs
and others, 1996, 1997a, 1999; Mason and others, 1997;
Aleinikoff and others, 1999), but some are presented here for
the first time.