Complex sentence: The McMurray Formation was deposited by an extensive drainage system that flowed northward, following a regional north-south low that was created by the dissolution of thick salt deposits in the Devonian Elk Point Group deep within the subsurface.
Split into simpler sentences: The McMurray Formation was deposited by an extensive drainage system that flowed northward following a regional north-south depression. The depression was created by the dissolution of thick salt deposits in the Devonian Elk Point Group deep within the subsurface.