Date of Award

1970

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Geology

First Advisor

Dr. Frank R. Karner

Abstract

Large remnants of pediment surfaces in the unglaciated southwestern portion of North Dakota exhibit evidence of a former permafrost environment in the form of ice-wedge fillings and bedding contortions. Under proper moisture conditions the "fossil" polygonal pattern of the wedge fillings may be observed on air photos. The molluscan fauna collected from the fluvial deposits which cover the pediment surfaces indicates that there was a relatively warm, moist climate during the time of deposition. Because of paleontological, topographic, and geomorphic evidence, it is suggested that the two sites of Tuthill, Laird, and Frye (1964) are not correlative and that one of them, the Marple Ranch site, correlates with the two sites of this study. Although age determinations based upon Pleistocene mollusks are generally considered unreliable, the pediment deposits are tentatively designated as Sangamon in age and the permafrost features are considered to be early Wisconsin.

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