Steep upward gradients like this allow Madison water to escape to the surface along fracture zones or breccia pipes in ... City Lake had to be removed, but frequent stage measurements have been made since by National Park Service staff. ... Long-term drainage of the aquifer at Wind Cave has been interpreted by Ford et al. (1993) from U/Th dating of calcite deposits at various elevations. The mean rate of water-table lowering has been ~40 cm/1000 yrs over the past 400, 000 years.
|Title||:||Select Field Guides to Cave and Karst Lands of the United States|
|Author||:||Annette Summers Engel, Scott A. Engel|
|Publisher||:||Karst Waters Institute - 2009-07|