2. n. [Heavy Oil]
In the context of heavy oil, an oil sand is a porous rock layer, often considered to be a mixture of sand, clay, water, and bitumen. The term is predominantly used in Canada, where over 170 billion barrels of bitumen are estimated to be held by large oil sand deposits in the Athabasca, Cold Lake, and Peace River regions of Alberta. Oils from such sands may have a gravity of less than 10° API. Both in situ recovery and mining methods are used to extract the resource, with surface mining used for extracting deposits of extraheavy oil at shallow depths of less than 100 m [328 ft].