Coffee Rock

As Coffee skirt (English for coffee rock) like stone hardened sand are referred to in Australia occurring largely impermeable formations.

Sediments of sand and organic materials that have been deposited by rivers during the Pleistocene, formed these formations. The material has a solid, resembling coffee grounds, texture and grain, as well as, caused by humic substances, dark brown - black color.

Coffee rock is manifest days at some beaches in New South Wales and southeastern Queensland (including Fraser Iceland ). Especially on Fraser Iceland seals the layer of coffee rock from the numerous lakes and prevents the rapid infiltration of precipitation.