Paper No. 33-0
NATURE AND ORIGIN OF BURIED ICE WITHIN A RECESSIONAL MORAINE, MATANUSKA GLACIER, ALASKA
JOHNSON, Justin J., Geology Department, Gustavus Adolphus College, 800 West College Ave, St. Peter, MN 56082, jjohnso4@gac.edu, BAKER, Gregory S., Department of Geology, Univ at Buffalo, 876 Natural Sciences Complex, Buffalo, NY 14260-3050, STRASSER, Jeffrey C., Augustana College, 639 38th St, Rock Island, IL 61201-2296, and ENSMINGER, Staci L., Department of Geology and Geography, Northwest Missouri State Univ, Maryville, MO 64468

A recessional moraine near the terminus of the Matanuska Glacier, Alaska displays characteristics of being ice-cored. Data collected by ground penetrating radar (GPR) revealed a continuous layer of buried ice within a portion of the recessional moraine. The stagnant ice is overlain by two to six meters of reworked sediment, initially deposited as the melt-out from the basal zone. A combination of a geomorphologic map of the area and the 3-D topographical surface of the top of the buried ice created with the GPR data provides a detailed picture of the nature of this ice-cored moraine. Field observations of the nearby active ice-margin indicate that deposition of sediment is occurring on the surface of the stagnating ice. The local topography is such that the ice margin is at a lower elevation than the older moraine due to the overdeepening of the glacier. The backwasting of the older, ice-cored moraine produces the sediment flows that run downslope towards the active ice-margin, covering the surface of the stagnating ice. The continual deposition of these sediment flows will significantly reduce the melting rate of the underlying ice. As the ice-margin recedes, the buried ice will be abandoned and stagnant, producing an ice-cored moraine. This study provides a model of ice-cored moraine genesis that could be applied to similar recessional moraines, and demonstrates that GPR can be an important tool to study shallow buried ice.

North-Central Section (36th) and Southeastern Section (51st), GSA Joint Annual Meeting (April 3–5, 2002)
Session No. 33--Booth# 39
Undergraduate Research (Posters)
Heritage Hall: East
1:00 PM-5:00 PM, Thursday, April 4, 2002
 

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