Marl lake

A marl lake is a type of alkaline lake whose bottom sediments include large deposits of marl, a mixture of clay and carbonate minerals. The term is particularly applied to lakes that have been dredged or mined for marl, often for manufacturing Portland cement. Marl lakes are found around the Great Lakes of North America, in Britain, and in other areas that were once glaciated. They support distinctive ecological communities that are vulnerable to damage from silting, nutrient pollution, drainage, and invasive species.