Features of the genesis of Jewel Cave and Wind Cave, Black Hills, South Dakota

Jewel Cave and Wind Cave, South Dakota, are here interpreted as multi-storey dissolutional mazes created during the present erosion cycle by deep phreatic waters that ascended through them. They formed where such groundwaters were focused to discharge through weaknesses in an overlying sandstone formation. The multi-storey structure is created by occurrence of different joint systems in adjacent beds or greater units, with inter-storey blocking layers such as thin clays often playing a role. In such structures, lower storeys tend to be more extensive; upper storeys may contain both outflow and adventitious components. Mixing corrosion effects and migration of springs can complicate upper storeys. As such caves drain, condensation corrosion facets and pockets may be created. From U series dating and magnetic studies of normal speleothems and of subaqueous calcite encrustations, Jewel Cave drained more than 350 000 years ago. -from Author