STRUCTURAL INFLUENCES ON PAST AND CURRENT CAVE DEVELOPMENT IN UPPER DAVIS CREEK, NEWTON COUNTY, ARKANSAS

Cave exploration and detailed mapping in Upper Davis Creek, Newton Co., Arkansas, have revealed numerous structural features in limestone of the Boone Formation that heretofore were previously unknown. These features range from a great variety of slightly-tilted rocks (dips generally less than several degrees) to dozens of fault features, only a few of which are of a magnitude to be shown on the published geological quadrangle maps. Although most of these are not regional in scale, they appear to be very important at controlling groundwater flow that formed cavern passages.

Cave erosional features and deposits have been found that indicate past episodes of thermal groundwater circulation. These include upper-level paleo cave passages and chambers, now reactivated by present-day stream drainage, dolomite breccia linings, and frequent calcite crystals, some of which are as long as 1.9 meters. Although the source of the thermal water is not known with certainty at this time, the proximity of these features and deposits to deep basement faults is consistent with upwelling of deep basin brines.

Groundwater tracing indicates that all of the water that currently sinks into the Boone Formation along upper Davis Creek flows through the complex Chilly Bowl Cave to resurge at an unnamed spring in the creekbed where sandstone of the basal Everton Formation has been brought to the surface. This flow continues down Davis Creek, partially sinking to emerge from Yardell Spring, then sinks again to finally emerge at Mitch Hill Spring before joining the Buffalo River. However, underground drainage divides have been discovered in some nearby caves, suggesting that the overall subterranean drainage system is much more complex than was initially conceptualized.