It was deposited on an alluvial to coastal plain adjacent to the Bearpaw Sea, an inland sea that gradually transgressed across the region, depositing the marine shales of the Bearpaw Formation that overlie the Dinosaur Park Formation.
It was deposited on an alluvial to coastal plain by river systems that flowed eastward and southeastward to the Bearpaw Sea, a large inland sea that was part of the Western Interior Seaway. That sea gradually inundated the adjacent coastal plain and deposited the marine shales of the Bearpaw Formation on top of the Dinosaur Park Formation.