Eramosa Karst, Protected geological area in Stoney Creek, Canada

Eramosa Karst is a provincially significant Earth Science Area of Natural and Scientific Interest in Stoney Creek, Hamilton, Ontario, just south of the Niagara Escarpment. It contains sixteen karstic features, including five caves, sinkholes, and karst windows, formed in dolomite of the Lockport Formation. The Eramosa Escarpment crosses the site, with cliffs up to 3 metres high.

The karst landscape formed roughly 13,000 years ago when the last glacier left the region and water began carving pathways through limestone. This water-and-stone system developed into the complex underground network visible today.

The name Eramosa comes from the Eramosa River, which does not flow through the site; the karst lies in the Eramosa watershed. Visitors can see how streams disappear into sinkholes and reappear at springs, and how plants and animals live on this dolomite terrain.

The area is open daily from sunrise to sunset with parking available nearby. Wear sturdy shoes since trails can be uneven and you may encounter rough ground and muddy sections.

Nexus Cave, at 335 metres, is the longest of the five caves at Eramosa Karst and ranks as the 10th longest cave in Ontario. Pottruff Cave's entrance is a karst window, formed when the bedrock roof of a cave collapsed. Most sinkholes here are suffusion dolines, depressions created above cavities in loose glacial sediment.