The images above show slow growth between 19, followed by a decade of more rapid development. Great Canadian Oil Sands opened the first large-scale mine in 1967, but growth was slow until 2000 because the global cost of a barrel of oil was too low to make oil sands profitable. It takes two tons of sand to produce one barrel of crude oil. The process of extracting oil from the sand is expensive. The sand is rinsed with hot water to separate the oil, and then the sand and wastewater are stored in “ tailings ponds,” which have smooth tan or green surfaces in satellite images. To extract the oil at these locations, oil producers remove the sand in big, open-pit mines, which are tan and irregularly shaped.

The Athabasca River runs through the center of the scene, separating two major operations. These images from Landsat satellites show the growth of surface mines over the Athabasca oil sands between 19. While conventional oil has held steady, oil sands output has gone up from 1 million barrels per day in 2005 to 2.4 million barrels per day in 2015. Since then, oil sands production has outpaced conventional oil production. In 2010, surface mines produced 356.99 million barrels of crude oil, while in situ production (the hot water wells) yielded 189.41 million barrels of oil. The rest of the oil sands are buried more than 75 meters below ground and are extracted by injecting hot water into a well that liquefies the oil for pumping. Only 20 percent of the oil sands lie near the surface where they can easily be mined, and these deposits flank the Athabasca River. According to a 2003 estimate, Alberta has the capacity to produce 174.5 billion barrels of oil.

Bitumen-a very thick and heavy form of oil (also called asphalt)-coats grains of sand and other minerals in a deposit that covers about 142,200 square kilometers (54,900 square miles) of northwest Alberta.

Buried under Canada’s boreal forest is one of the world’s largest reserves of oil.

Sand of time mount