Geologists rarely find the information they need laying around on the surface of the earth because erosion, land movements, and organic
deposits continuously bury the surface. When the evidence is hidden under layers of sediment or water, often the easiest way to get at
it is to take cores. A core is a vertical section removed from the ground by plunging a hollow cylinder into the sediment (in some
cases the top of the tube is closed off to create suction) while lifting the tube out again. Every day, small children cover straws
with their fingers to lift liquid out of a glass, essentially taking cores from the contents of the glass.There are many different types of coring devices, depending on the size of sample needed, the hardness of the material being cored and the accessability of the core site. Typically, lake coring equipment is portable enough to be hand-carried over several miles of rough terrain. Often the coring is done in winter on ice-covered lakes to eliminate the need for a boat or coring platform. Bear Lake doesn't freeze over every year, so all our lake cores have been taken using a floating platform, similar to the one illustrated here.
In September 2000, a new type of coring rig being built in Salt Lake City will be tested at Bear Lake, prior to its use in Africa and South America. The GLAD800 corer is intended for large lakes and funds for the development are from international science groups, including the National Science Foundation (NSF). The USGS is making use of this opportunity and is integrating the testing phase of the GLAD800 project with the Bear Lake Project. Although immediate goals are to study recent events, the Bear Lake GLAD800 cores may extend our record back a million years or more.
The following are different types of cores:
U.S. Department of the Interior | U.S. Geological Survey
URL: http://esp.cr.usgs.gov/info/lacs/coring.htm
Page Contact Information: ESP Web Team
Page Last Modified: Wed 2-May-2001 10:08:14 MDT