Karsts are geological formations including underground drainage, caves and passages caused by dissolving rock, found in limestone formations like the Niagara Escarpment. The Eramosa Karst contains examples of 16 different karst features and the Ontario Ministry of Natural Resources designated the Eramosa Karst lands as an Area of Natural and Scientific Interest in 2003. It is believed to have the largest number of unique karst features in any single area in the province.
Several of its karst features are provincially significant, including: soil pipes, a high concentration of suffosion dolines and sinking streams, overflow sinks, dry valleys and a 335-metre-long cave (the tenth longest in all of Ontario). There is also a natural dolomitic limestone bridge at the entrance of one of the sinkholes. The surface and groundwater drainage system that created the karst originated about 13,000 years ago, after the last glacier retreated. Today the drainage system sustains the karst and provides examples of karst processes and features in different stages of development.