Tar sands, also known as oil sands or bituminous sands, are a mixture of sand, water and clay with a dense, sticky, semi-solid form of crude oil called bitumen. Although very similar in appearance, technically bitumen is not the same as tar, which is a man made product. Bitumen needs to be heated or diluted to make it ow, which distinguishes it from 'extra-heavy crude', another form of high density unconventional oil, the largest deposits of which occur in Venezuela's Orinoco Belt (see 'Extra heavy oil' in 'Other Unconventional Fossil Fuels' factsheet).
Most of the world's tar sands are found in Canada where extraction is taking place on an enormous scale, with devastating e ects on the local environment and critical implications for climate change. Most of the Canadian tar sands are in three major deposits in Northern Alberta which together cover more than 140,000 km2, an area larger than England. In 2011, Alberta's bitumen production reached over 1.7 million barrels (270,278 m3) per day.1
Tar sands also occur in other parts of the world, with the next largest deposits in Kazakhstan and Russia. Explor- ation and test projects have been carried out in Russia, Madagascar, Congo (Brazzaville), and Utah in the USA.