Reports

Geology and karst development of the Hagerstown Valley (Great Valley) of Maryland

This report summarizes findings of a multi-year study, conducted by the Maryland Geological Survey and sponsored by the Maryland State Highway Administration Office of Materials Technology, on the relationship between geology and sinkhole development in the Hagerstown Valley.
Approximately 3,800 karst features were identified and located using a Global Positioning System (GPS).
Active sinkholes make up 20% of the total number of features, while depressions and springs comprise 66% and 9%, respectively.
There is an identifiable relationship between the types of karst features and the bedrock units in which they occur; this relationship allowed development of a karst susceptibility index (KSI) for rocks of the Hagerstown Valley.
High KSI rock units include the Stonehenge Limestone, St. Paul Group, Rockdale Run Formation, and the Chambersburg Formation. The Tomstown, Waynesboro, and Elbrook formations, and Pinesburg Station Dolomite had low KSI numbers.
The impact humans have on karst development are substantially less than that observed in the Frederick Valley of Maryland.
With this understanding of the relationship between geologic variables and karst development, an a priori knowledge about areas that pose a high risk for sinkhole potential can be utilized as a foundation on which any future site-specific study can be built.