Lee Clayton

Date of Award

1960

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Geology

Abstract

Kidder County, located in south-central North Dakota, is completely covered by drift of the Wisconsin stage. Irregular preglacial topography, large amounts or confusing “stagnation” moraine, and a blanket of outwash over much of the county make differentiation of tills of different glacial advances difficult. The purpose of this report is finding ways of lithologically differentiating the tills of the different glacial advances in the county.

Kidder County is covered by drift of two major advances of the Mankato substage, A-1 and B-1 of Flint’s South Dakota designation. A dark brown, sandy, loesslike material covering much of the county probably is the same material overlying carbon 14 dated wood in the southeast part of the county. Yellow loess is exposed in at least four places in the county.

Grain analyses on 55 samples of till from throughout the county showed no significant differences in the size composition of tills of the A-1 and B-1 advances. Fifteen pebble counts failed to show any differences between the tills of the two advances. The field appearances of tills of the two advances do not differ appreciable. However, where two tills crop out in one exposure in the southern part of the county, the lower till is yellower, stickier, and harder than other tills in the county and has small irregular joints coated with iron and manganese oxide. This till is thought to be Tazewell in age. In a second exposure two tills are separated by gravel concentrate which is overlain by less than a foot of loess. These two tills probably belong to the Long Lake and Twin Buttes loops of the A-1 advance of the Mankato substage.

The only way to differentiate tills within the Mankato substage in the end moraine complex of south-central North Dakota is by the topographic expression and stratigraphic relationships of the till sheets. In some cases Mankato and Tazewell tills may be differentiated by secondary changes such as the degree of oxidation and joint coatings. The percentages of sand and the percentages of shale in the coarse sand fraction of samples of till collected from the county were not found to vary appreciably for 15 miles on either side of the contact between the Fox Hills sandstone and the Pierre shale. This helps to strengthen the belief of other workers that only 20-30% of till is locally derived.

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