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The oil sands refining process is labourious and uses a lot of energy compared to mining conventional oil.

This single mine in the Athabasca oil sands produces 260,000 barrels of oil a day. It is one of several mines in the Athabasca area. Note the proximity of the open pit mine to the river.

Syncrude's oil sands plant at Athabasca, one of the larger sites in the region.

Bitumen is thick and viscous, very difficult to transfer via pipeline without being diluted.

Once it has been processed, bitumen becomes synthetic oil - a light crude oil that can be used for many different purposes.

The oil and sand are separated in water before the oil can be processed.

A surface mine in Athabasca. The blue buildings are the first stage processing plants.

Here, the tar sand is particularly wet. Usually, it is mostly dry and nearly solid, similar to thick clay.

It is thought that there are 1.7 trillion barrels worth of oil in Alberta, though only 10% of this is currently recoverable.

Athabasca in 1989. Only three large surface mines are visible. Today, the mines cover 420 square kilometres.

The Athabasca oil sands are the largest of three oil sands in Alberta, covering 140,000km².

c. 1915 - Mining the oil sands on the banks of the Athabasca River.

Bitumen stays solid at room temperature. This lump has been separated from sand with hot water.

A hydraulic shovel fills a truck with oil sand.

Surface mining in the Athabasca oil sands. The mines are positioned next to the Athabasca River because the water is used to separate the oil from the sand.

Enormous diggers carry 300 tonnes of oil sand at a time to be processed.

The chimneys of the oil sands processing plant.

The tyres of the diggers at the oil sands are the largest in the world. They each cost $50,000 and must be replaced each year. Every digger has six wheels.

The trucks used to transport the raw oil sands are some of the largest in the world - about the size of small fishing trawler boats.

The open pit mines cover vast areas. A huge amount of machinery is needed to extract the solid oil sand beneath the boral forest.

The smokey chimneys of Alberta's oil refineries. Bitumen must be mixed with lighter oils before it can be refined into useful synthetic oil.

Each of these enormous trucks can carry 300 tonnes of oil sands at a time.

The Athabasca River running through the mines. Water is drawn from the river to be used in the extraction process.

Boreal forest, shown in dark green, covers almost 60% of Canada's land area.

The 'black gold' of the oil sands. This is thought to be one of the last large oil deposits on Earth.

Athabasca mine in 1992 surrounded by boreal forest.

Ten years later, the mine has grown significantly, developing along the length of the river and into the boreal forest.

A machine used for the old method of extracting the oil. These machines had extremely high levels of energy consumption. New techniques are being implimented that are more energy efficient.

Mining the oil sands is a vast operation, with a number of companies frequently opening new mines in the Athabasca region.

Fort McMurray, the mining boomtown near Athabasca. Population in this town grew from 2,000 in 1966 to 64,500 in 2006.

More than 400km² of boreal forest have been cut down to make space for the surface mines at Athabasca.