Athabasca oil sands open-cast mining area north of Fort McMurray, Alberta, Canada, comparison of satellite images taken in 1984 and 2011, respectively. In 1984 there is only one open-cast mine (Syncrude Base Mine, “Mildred Lake”) present in the area. In 2011 a total of 9 open-cast mines and four in-situ sites were operational or under construction.