The Burren: Turloughs (Dry Lakes)

These are grassy hollows, sometimes extending over many acres, which during wet weather fill with water through subterranean passages in the rock and empty by the same means. The rate of the rise and fall and the duration and frequency of the flooding varies in different turloughs, being dependant on several factors connected with underground drainage. These changes are in many cases quite rapid; an appreciable amount of water can collect in one hour, and disappear in an equally short time. Some turloughs hold permanent water on their floors, others show no water at all when flooding is absent, the bottom as well as the sides being covered with a rich green sward. Swallow holes set among the muddy moss-covered rocks often indicate the point of inflow and outflow.

A Turlough