Albian Sands Energy Inc. is the operator of the Muskeg River Mine, an oil sands mining project located 75 kilometres (47 mi) north of Fort McMurray, Alberta, Canada. It is a joint venture between Shell Canada (60%), Marathon Oil Canada (20%) and Chevron Canada (20%). The company's legal headquarters are located in the Shell Tower in Calgary, Alberta. Albian Sands got its name from the Albian Boreal Sea which, during the Albian stage of the Cretaceous (over 100 million years ago), moved over the McMurray sands and deposited a blanket of marine shale on its floor which trapped the hydrocarbons of the McMurray Formation. The oil sands resources of the Muskeg River Mine are a legacy of the Albian Sea.