THE POTENTIAL EXTENT OF THE JEWEL CAVE SYSTEM: FINE-TUNING A GIS MODEL

Previous research at Jewel Cave has shown a direct relationship between airflow at the entrance and the prevailing atmospheric pressure. This barometric airflow was used to estimate a total minimum cave volume of 1.1 x 10⁸ m³, of which less than three percent has been discovered.

The minimum areal extent of Jewel Cave was derived from estimated volume, as well as 1) the thickness and distribution of the Madison Limestone; 2) the potentiometric surface of the Madison aquifer; 3) the location and extent of potential geological obstacles; 4) the three-dimensional distribution of the cave systems within the host rock; and 5) the “cave density” at Jewel Cave and Wind Cave. Based on the calculated cave volumes and an estimated 9.3 x 10¹⁰ m³ of available limestone, the overall cave-to-rock ratio was calculated to be 0.18%. This was at the low end of the range of known “cave density” values for Jewel Cave and Wind Cave, 0.15-0.59%.

New field-mapping of geologic structures has given reason to revise the boundaries of the cave potential model. With these adjustments, it appears that more of the predicted volume must exist in an area between Jewel Cave and Wind Cave; and that the new predicted value for "cave density" correlates more closely with actual values for known cave passages. The new calculations strengthen the possibility that the two volumes could be part of one large cave system.

This research refines a tool that has successfully been used in support of efforts to protect the park's primary resource, even the portions that are as-yet undiscovered. Those efforts include two mineral withdrawals and a land exchange.