MAGNETOSTRATIGRAPHY OF CAVE SEDIMENTS, WYANDOTTE RIDGE, CRAWFORD COUNTY, INDIANA - TOWARDS A REGIONAL CORRELATION

The polarity of 42 sediment samples obtained from 21 sites in Wyandott e Cave and five smaller satellite caves in Wyandotte Ridge, southern I ndiana, is used as a basis for a magnetostratigraphic correlation with sediments in Mammoth Cave, Kentucky. Sediments in caves at elevations between 137 and 162 m have a normal polarity, but the fill between 16 8 and 171 m exhibits a polarity reversal. The reversal is interpreted to represent the most recent polarity change, suggesting that the uppe r level of Wyandotte cave was last active at about the same time (not less than 0.78 Ma) as the ''C'' level in Mammoth Cave which lies at ap proximately the same elevation, The local base level control in both c ave systems is provided by tributaries of the Ohio River. Thus, the co rrelation is most likely a consequence of the contemporaneous abandonm ent of upper-level passages in Wyandotte and Mammoth caves during the early Pleistocene reconstruction of the Ohio River drainage. Sediments in caves between 236 and 241 m have a normal polarity. The fill in th ese (Little Wildcat and Galley Door) caves is probably at least 2.6 Ma old. It appears to correlate with the residuum that delimits the Uppe r Mitchell Plain Surface (the Pennyroyal Plateau in Kentucky) and, on the basis of our interpretation of the magnetostratigraphy, is older t han the fill in the highest ( ''A'' and ''B'') levels in Mammoth Cave.