There may be as many as 503 billion barrels of oil in the Bakken Formation that runs under Saskatchewan, Manitoba, North Dakota and Montana
The Bakken Formation is a 350 million-year-old underground layer of rock that occurs in much of the Williston Basin, a vaguely heart-shaped warp in the otherwise flat prairies on the U.S.-Canada border. It was discovered in 1953 by a geologist named J.W. Nordquist and named after Henry Bakken, owner of the Montana farm where Nordquist first drilled.
Underneath the high, scrub-covered rangeland of northwest Colorado is the world's biggest oil field.