Sinkholes in Pennsylvania affect stream quality, groundwater quality and public health and safety.
Sinkhole - A hole or depression in the ground that results from surface material moving into subsurface pathways caused by the weathering process. A sinkhole occurs by either gradual subsidence to form a depression in the landscape or by collapse to form an abrupt break in the soil.
Karst - Description of a landscape developed upon limestone or dolomite rock. Karst is characterized by sinkholes, caves and underground drainage of water due to the dissolution (dissolving) of the rock. Other features of a karst landscape may include rock pinnacles, uneven bedrock surface, rolling terrain, swallets (where stream flow is lost into a hole), large springs, and surface depressions that won't hold water.