The threatened karst of the Great Western Lakes, Ireland

Limestone is a notoriously leaky rock. In many areas that are underlain by limestone, surface rivers are few and disjointed. They disappear into sinks only to reappear, sometimes many kilometres away, at springs. It is not an environment in which lakes are typically found. Some 40 percent of Ireland is underlain by limestone, yet the Irish lowlands are scattered with countless lakes, large and small. In many the limestone beneath is effectively sealed by a cover of glacial till; others have formed where hollows descend below a shallow water table. Around the shores of many, exposed limestone bedrock and boulders support a range of peculiar etched features that are virtually confined to this lakeshore environment.