THE NATURE OF GLACIAL RIVER WARREN FLOW: A STUDY OF THE CHARACTERISTICS OF BOULDERS AND BEDROCK IN THE BIG STONE NATIONAL WILDLIFE REFUGE, WESTERN MINNESOTA, TO DETERMINE OUTLET FLOW RATES
The goal of this research was to: 1) determine if boulders within BSNWR were of local origin or transported; 2) identify geomorphologic evidence of catastrophic flow; and 3) determine the relationship between the orientation bedrock forms and flow direction in this portion of the Minnesota River Valley. The methods used included the measurement of boulder dimensions and orientation, analysis of fluvial erosional features, detailed determination of boulder and bedrock lithologies, and comparisons of the BSNWR boulder lithologies to boulder lithology suites upstream (in Browns Valley, MN), and downstream (in Appleton, MN) in the Minnesota River Valley.
The results of this study show (1) the boulders in BSNWR are overwhelmingly similar to the underlying bedrock; (2) the boulders up- and downstream did not share a similar lithology with the boulders in the BSNWR; and (3) both the bedrock and boulders in the refuge show fluvial characteristic such as, fluvial polish, pot holes, and streamlined forms. The boulders in the BSNWR are more than likely corestones from the surrounding bedrock. The relationship between the boulders in the BSNWR and Glacial River Warren however is ambiguous.
Research for this study was funded by a grant from the N.S.F.-R.E.U Program (NSF-EAR 0640575).