Faculty Publications

Landscape Development as Indicated by Basin Morphology and the Magnetic Polarity of Cave Sediments, Crawford Upland, South-Central Indiana

Document Type

Article

Journal/Book/Conference Title

American Journal of Science

Volume

297

Issue

8

First Page

842

Last Page

858

Abstract

Paleomagnetic dates of sediment deposits in the Marengo Cave system and four caves in Wyandotte Ridge have been combined with the morphometric analysis of surface drainage basins in their vicinity to elucidate the timing and significance of geomorphic events affecting karst landscape development in the southern portion of the Crawford Upland in Crawford County, Indiana. Wyandotte Cave exhibits two distinct levels separated by a 24 m vertical gap. It is located near the Ohio River, which acts as the local and regional control on base level. The magnetostratigraphy suggests that the upper level of Wyandotte Cave was abandoned in the early to middle Pleistocene, following a drop in the regional base level that occurred no later than 0.78 Ma ago and accompanied the expansion of the Ohio River drainage system. Commensurate with the time taken for the effects of a drop in base level to propagate up-basin, it is likely the upper level in Marengo Cave was abandoned after the upper level in Wyandotte Cave was vacated (that is, ≤0.78 Ma ago). The smaller (7 m) separation between the upper and lower levels in Marengo Cave reflects the diminished influence that a drop in base level commonly has in locales relatively far removed from a basin outlet Greater stability of the landscape in the vicinity of Marengo Cave implies that there the subsurface and surface landforms are more mature than caves and drainage basins in close proximity to the Ohio River. Stability also facilitates the development of an extensive, integrated drainage system in basins buffered by distance from the full impact of base level lowering. In these basins, a further drop in base level will likely be absorbed by the subsurface portion of the drainage network. Therefore, in the Crawford Upland, evolution toward a karst plain will progress more rapidly in tributary drainage basins that are relatively far removed from the Ohio River.

Department

Department of Geography

Original Publication Date

1-1-1997

DOI of published version

10.2475/ajs.297.8.842

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