Title

Knickpoint analysis of streams in North Dakota, South Dakota, and Nebraska

Date of Award

1997

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

J.R. Reid

Abstract

Analysis of stream profiles, seismic reflection studies, engineering studies, and historical earthquakes indicates uplift in south-central South Dakota and north-central Nebraska over the last 5-10 ma. The purpose of this study was to determine if this uplift could be detected by constructing topographic profiles along, and in close proximity to several streams in this region. The Cannonball River, ND, was used to compare the streams in South Dakota and Nebraska to a stream beyond the affected area.

Data for the profiles were collected from 7 .5 minute topographic maps as well as GPS surveys. Abrupt changes in slope (irregularities) were determined along the profiles based on visual inspection and spreadsheet calculation. The use of spreadsheet calculation assured consistency in identification of irregularities among profiles.

Profiles constructed along and in close proximity to streams in the study area contain numerous irregularities. In general, the profiles in close proximity to the streams (land surface profiles) show more irregularities than stream profiles. This is partly related to the method of construction of land surface profiles. Examination of the profiles has shown that some of the identified irregularities are the result of lithologic changes while others are the result of tributary streams. However, the reasons for many of the irregularities, which may include recent uplift, are not apparent and need to be field checked. Future work should also involve collection of more data through GPS surveying, which would increase the data base from which profiles can be constructed.

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