The Athabasca Oil Sands are large deposits of bitumen, or extremely heavy crude oil, located in north-eastern Alberta, Canada roughly cantered around the boomtown of Fort McMurray. These oil sands, hosted in the McMurray Formation, consist of a mixture of crude bitumen (a semi-solid form of crude oil), silica sand, clay minerals, and water. The Athabasca deposit (also known colloquially as the Athabasca Tar Sands although there is no actual tar) is the largest reservoir of crude bitumen in the world.

It is also the largest of three major oil sand deposits in Alberta, along with the nearby Peace River and Cold Lake deposits. Together, these oil sand deposits lie under 141,000 square kilometres (54,000 sq mi) of sparsely populated boreal forest and muskeg (peat bogs) and contain about 1.7 trillion barrels (270×10^9 m3) of bitumen in-place, comparable in magnitude to the world's total proven reserves of conventional petroleum. With modern non conventional oil production technology, at least 10% of these deposits, or about 170 billion barrels (27×10^9 m3) were considered to be economically recoverable at 2006 prices, making Canada's total oil reserves the second largest in the world, after Saudi Arabia's. The Athabasca deposit is the only large oil sands reservoir in the world which is suitable for large-scale surface mining, although most of it can only be produced using more recently developed in-situ technology. (From: Earth Snapshot)

The image below acquired from GeoEye and available in Google map shows a detailed view of the area.

This image, taken by the Envisat satellite (Full Resolution, MERIS_FR), shows details of the area using three band combinations (7, 5, 2). The plume of smoke is very evident to the north of the area (centre image), and the different shades of the smoke are a result of different materials burning.

This image was created by merging two ERS-1/2 SAR images and one Envisat WSM image, acquired on different dates (1992, 2000 and 2010). This mosaic was made with images acquired along the Athabasca River, and shows large deposits of oil sands located along the lower River, near Fort McMurray. The infrastructures are highlighted in red and green to show the different acquisitions.