Karst topography

 

Based on the sources and our conversation history, Karst topography is a distinctive landscape that develops primarily in areas underlain by soluble bedrock, most notably limestone [14, 35, 39, 43, 66, Conversation History]. It is characterized by features formed by the dissolution of this rock by water.

Key features of karst topography mentioned in the sources include:

• Numerous sink-holes (also referred to as sinks or closed depressions) [6, 35, 38, 39, 43, 63, 66, 67, 68, 102, 134, Conversation History]. These are depressions on the surface that can be funnel-shaped. A common type of sink-hole in Greenbrier County is due to the collapse of the roof of underlying caverns, resulting in sinks that are quite irregular in shape, often elongated, usually steep-walled, and sometimes quite large. In the Pecos Valley, New Mexico, they are described as closely spaced sinks or closed depressions, some very deep holes, caused by the collapse of cave or solution cavity roofs. Sinkholes in Pocahontas County can be points where small streams disappear.
• Caverns (or caves, solution cavities) [6, 35, 39, 43, 61, 67, 68, 134, Conversation History]. These are underground waterways or immense caverns eaten into the limestone beds. The process involves rainwater charged with acids, such as vegetable acids or carbonic acid, which dissolves the limestone, widening every crevice it finds. Carlsbad Caverns is noted as a spectacular example of a solution cavity in limestone.
• Underground streams or subsurface drainage [3, 35, 39, 43, 102, Conversation History]. In karst areas, surface streams may be few, as water sinks into the ground. The sunken waters can reappear in great springs at a lower level. Subsurface drainage on the Greenbrier Limestone is mentioned as a feature in Greenbrier County.
• A relatively low relief and the general absence of an interconnecting valley system in some karst areas.

Karst topography is explicitly stated to be typically developed in Greenbrier County where the outcropping rocks are limestones of the Greenbrier Series. West of the Greenbrier River in Greenbrier County, subsurface drainage on the Greenbrier Limestone is a notable feature. While the term "karst" is used specifically for Greenbrier County and the Pecos Valley, New Mexico, the descriptive features like sinkholes and caverns formed in limestone are mentioned in other areas as well, including Pendleton County, Bath County, Rockbridge County, and Pocahontas County. In the Edwards Plateau, Texas, the landscape created by ground water dissolving limestone to form solution cavities (caves and sinks) is described.