Tar sand, also known as oil sand, is a type of sedimentary deposit that contains a mixture of sand, clay, water, and a dense, viscous form of petroleum called bitumen. Tar sands are significant in economic geology for understanding unconventional oil resources, the processes of oil extraction, and the environmental impacts of tar sand mining.
Reference: Mossop, G. D., & Shetsen, I. (1994). “Geological Atlas of the Western Canada Sedimentary Basin.” Canadian Society of Petroleum Geologists.