Stratigraphy of Lacustrine Sediments Cored in 1996, Bear Lake, Utah and Idaho

The overall goal of our research on Bear Lake is to create records of past
climate change for the region, including changes in precipitation (rain and
snow) patterns during the last 10,000 years and longer. As part of the project,
we are attempting to determine how the size of Bear Lake has varied in the
past, to assess the possibility of future flooding and drought. We also seek to
understand human influences on sediment deposition, chemistry, and life in the
lake.

Evidence of past conditions comes from sediments deposited in the lake, so
reconstruction of past conditions requires accurate dating of the sediments.
The study includes the upper Bear River watershed as well as Bear Lake itself.
The Bear River is the largest river in the Great Basin and the source of the
majority of water flowing into the Great Salt Lake. In this region, wet periods
may produce flooding along the course of the Bear River and around Great Salt
Lake, while dry periods, or droughts, may affect water availability for
agricultural, industrial, and residential use.

This report describes the stratigraphy of sediments beneath Bear Lake along a
transect of cores obtained in 1996. The stratigraphy is derived mostly from
high-resolution acoustic-reflection profiles, supplemented by analytical
information from cores that indicate correlations among various horizons. The
deep drill hole obtained in 2000 (BL00-1) also is along the same acoustic
profile, so the stratigraphy of its upper part also is described in relation to
the 1996 cores.

[Summary provided by the USGS.]