|Rimstone dams (or gours) are calcite or other mineral barriers that
pond streams or shallow pools in caves. They tend to form stairsteps when
in a series, and often extend into flowstone
deposits above or below (as in the second photo in the group of smaller images). Often flowstone
is festooned with tiny micro-gours on horizontal surfaces.|
When dams form under running water, they tend to be higher when the passage is steeper. Shallow-gradient dams tend to be lower and more sinuous in nature. Rimstone is one of the most common cave formations, after flowstone, stalactites, and stalagmites.
Rimstone dams form where there is some gradient, and hence flow, over the edge of a pool. Crystallization begins to occur at the air/water/rock interface. The turbulence caused by flow over the edge of the building dam may contribute to the outgassing or loss of carbon dioxide from water, and result in precipitation of mineral on this edge.
Choose a thumbnail to zoom in on more images of rimstone
|Created: June 19, 1995|
Last Updated:May 4, 2005
Author: Djuna Bewley