Buried just beneath a layer of muskeg and forest in northern Alberta, Canada, lies a 50,000 square mile reservoir of heavy crude oil, possibly holding 2 trillion barrels of recoverable oil. These bitumen deposits require a lot of effort to extract, recover, and pre-process before the oil can be sent to conventional refineries. Most of the current extraction process takes place in open-pit mines, with massive machinery scraping up the tarry sandstone and moving it to facilities for processing. As the name "tar sands", or oil sands, implies, the heavy crude is found mixed in with sand, clay, and water, which must be removed, then the heavy crude must be "upgraded" to reduce viscosity and improve quality. Environmental activists have expressed concerns about the mining for years, citing destructive impacts on the land, the heavy carbon footprint of the laborious extraction and upgrade process, massive amounts of toxic byproducts, and studies that show oil sands crude emits more greenhouse gases than conventional crude oil. Oil companies continue to make efforts to reduce carbon emissions, manage toxic byproducts, and reclaim mined land, while ramping up production. The Alberta tar sands are currently producing around two million barrels of oil per day, with plans to increase that to nearly four million barrels per day by 2022. Reuters photographer Todd Korol recently traveled to Alberta to photograph some of the mines, facilities, and surrounding landscape.

1. The top layer of muskeg and earth (right), and the underlying tar sands (left) after the removal of the muskeg, at the Syncrude tar sands operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
2. Oil goes into a tailings pond at the Suncor tar sands operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
3. Giant dump trucks haul raw tar sands at the Suncor tar sands mining operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
4. An aerial photograph of petroleum byproducts spread out near the Suncor tar sands operations on September 17, 2014.
Reuters/Todd Korol
5. The Suncor tar sands processing plant near the Athabasca River at their mining operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
6. Pipelines run at the McKay River Suncor oil sands in-situ operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
7. Jack Pine trees grow near the Suncor tar sands mining operations on September 17, 2014.
Reuters/Todd Korol
8. Tanks stand covered in oil at the first step of separation at the Suncor processing plant near Fort McMurray on September 17, 2014.
Reuters/Todd Korol
9. A window shows a view of the first phase of oil being separated from the sand at the Suncor tar sands processing plant on September 17, 2014.
Reuters/Todd Korol
10. Oil at the first phase of separation from the sand at the Suncor tar sands processing plant on September 17, 2014.
Reuters/Todd Korol
11. Oil runoff at the Suncor tar sands processing plant on September 17, 2014.
Reuters/Todd Korol
12. A close view of oil at the first phase of separation at the Suncor tar sands processing plant on September 17, 2014.
Reuters/Todd Korol
13. A scarecrow stands to keep birds from landing on oil ponds at the McKay River Suncor oil sands in-situ operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
14. Worker camp housing projects at the Suncor Firebag in-situ oil sands operations on September 17, 2014.
Reuters/Todd Korol
15. A construction site at the new Suncor Fort Hills tar sands mining operations near Fort McMurray on September 17, 2014.
Reuters/Todd Korol
16. Giant dump trucks haul raw tar sands to be processed at the Suncor tar sands mining operations on September 17, 2014.
Reuters/Todd Korol
17. Giant earth moving equipment in the Syncrude tar sands mining operations near Fort McMurray on September 17, 2014.
Reuters/Todd Korol
18. Giant dump trucks haul raw tar sands near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol
19. A tailings pond near the Syncrude tar sands operations on September 17, 2014.
Reuters/Todd Korol
20. Giant dump trucks are loaded with raw tar sands at the Suncor tar sands mining operations on September 17, 2014.
Reuters/Todd Korol
21. Heavy equipment works in a tailings pond at the Suncor tar sands operations on September 17, 2014.
Reuters/Todd Korol
22. A log lays in a tailings pond at the Suncor tar sands operations near Fort McMurray on September 17, 2014.
Reuters/Todd Korol
23. New pine trees grow on reclaimed land that was once mined by Suncor at their tar sands operations near Fort McMurray on September 17, 2014.
Reuters/Todd Korol
24. A tailings pond near the Syncrude tar sands operations on September 17, 2014.
Reuters/Todd Korol
25. Conveyor belts move raw tar sands for processing at the Suncor tar sands operations on September 17, 2014.
Reuters/Todd Korol
26. An oil sands worker checks the oil during the first step of separation at the Suncor processing plant at their tar sands operations near Fort McMurray, Alberta, on September 17, 2014.
Reuters/Todd Korol