Gilgai

A gilgai is a small, ephemeral lake formed from a surface depression in expanding clay soils. Gilgai is also used to refer to the overall micro-relief in such areas, consisting of mounds and depressions. The name comes from an Australian Aboriginal word meaning small water hole. The pools are commonly a few metres across and less than 30 cm (12 in) deep but, in some instances, they may be several metres deep and up to 100 m (330 ft) across. Gilgais are found worldwide wherever there are cracking clay soils and marked wet and dry seasons. Gilgais are also called melonholes, crabholes, hogwallows, or puff and shelf formations.

A gilgai landscape, Queensland