Karst Spring Cutoffs, Cave Tiers, and Sinking Stream Basins Correlated to Fluvial Base Level Decline in South-Central Indiana

The Mitchell Aquifer averages 80m in thickness and underdrains a karst region in the Crawford Upland and Mitchell Plateau region in south-central Indiana (110,000 km2). The Springville Escarpment is a transitional boundary between the upland and plateau. Cave stream linking between cave tiers in the aquifer and correlation of cave tier inception horizons to a base level decline surface is interpreted for the Kirby Watershed, encompassing the prekarst headland of Indian Creek (42km2). The watershed was severed from lower Indian Creek at Eller Col by limestone cavern drainage on the ridge between White River and East Fork. Correlation of recharge basin topography and cave tiers is possible owing to the observation of 55 karst springs confined to lithostratigraphic contacts at three spring stratigraphic levels. Karst Spring Cutoffs are a specific type of vadose canyon diverting cave streams, bypassing around springs and passing into the laterally offset cave streams in the next lower cave tier. Cutoffs connect upper to middle tier cave streams and middle to lower tier cave streams as they enlarge below sinking stream basins and tributary spurs. Three speleogenic enlargement cycles characterize the eastern Leonard Springs Area, but only two cycles have enlarged in the western Garrison Chapel Area.