Edmonton Group

Edmonton Group Stratigraphic range: Late Cretaceous to Early Paleocene PreЄ Є O S D C P T J K Pg N
Horseshoe Canyon Formation of the Edmonton Group
Type	Geological formation
Sub-units	Scollard Formation, Battle Formation, Whitemud Formation, Horseshoe Canyon Formation
Underlies	Paskapoo Formation
Overlies	Bearpaw Formation, Belly River Group
Thickness	328 metres (1,076 ft) to 763 metres (2,503 ft)
Lithology
Primary	Sandstone, shale
Other	Bentonite, coal
Location
Region	Alberta
Country	Canada
Type section
Named for	Edmonton
Named by	Joseph Tyrrell, 1887

The Edmonton Group is a Late Cretaceous (Campanian stage) to early Paleocene stratigraphic unit of the Western Canada Sedimentary Basin in the central Alberta plains. It was first described as the Edmonton Formation by Joseph Burr Tyrrell in 1887 based on outcrops along the North Saskatchewan River in and near the city of Edmonton. E.J.W. Irish later elevated the formation to group status and it was subdivided into four separate formations. In ascending order, they are the Horseshoe Canyon, Whitemud, Battle and Scollard Formations. The Cretaceous-Paleogene boundary occurs within the Scollard Formation, based on dinosaurian and microfloral evidence, as well as the presence of the terminal Cretaceous iridium anomaly.

The Edmonton Group is present in the central plains of Alberta. It consists of sedimentary rocks that were deposited in nonmarine to brackish water environments between the Canadian Rockies in the west and the Western Interior Seaway to the east. Its reaches a maximum thickness of 763 metres (2,503 ft) near the foothills of the Rockies in the west, and thins eastward to zero at its erosional edge east of Edmonton.