Karst Potential Classification
The karst potential map shows the tendency for geologic units to develop or have karst
features such as sinkholes, springs, caves, or other solution conduits. The classification is
based on lithology. The lithologic characteristics used are percentage of CaCO3 in the
carbonate portion of the unit, grain size, bedding thickness, and insoluble components.
Insoluble components may occur as a mineral phase of the limestone lithology or as
interbeds of noncarbonate rock. These criteria were evaluated for all rock units and
combined rock units that appear on the map, and resulted in about 50 distinct rankings.
These rankings were reduced to five simplified classes by analysis of their frequency of
distribution.
VERY HIGH
Thick-bedded, typically fine-grained and pure limestone units with little or no
insoluble content. Will exhibit mature karst, including caves, sinkholes, and springs
where they crop out.
HIGH
Limestone units with low insoluble content, but varied grain size and bedding
characteristics. Likely to contain karst features. Occurrence of caves may be dependant
on physiographic setting, unit thickness, and lithology.
MEDIUM
Limestone units and coarse-grained, or siliciclastic units with limestone interbeds.
Limestone units may contain a high percentage of insoluble components. Siliciclastic
units will only be karst-prone where limestone beds occur in the near surface.
Development of karst features in this category is variable and dependent on site-specific
conditions.
LOW
Siliciclastic units with minor limestone beds or units primarily composed of
dolomite. Karst features are poorly developed or absent.
NONKARST
Consolidated or unconsolidated siliciclastic units. Karst features rare or absent.
*Note: A more detailed and precise karst classification method is in development. When
the testing and evaluations are complete, the method will be used to add enhanced
categories in the karst classification.