St. Mary Reservoir

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St. Mary Reservoir
Location Cardston County, Alberta
Coordinates 49°19′15″N 113°12′42″W / 49.32083°N 113.21167°W / 49.32083; -113.21167Coordinates: 49°19′15″N 113°12′42″W / 49.32083°N 113.21167°W / 49.32083; -113.21167
Basin countries  Canada
Max. length 7.9 km (4.9 mi)
Max. width 9.9 km (6.2 mi)
Surface area 37.5 km2 (14.5 sq mi)
Average depth 10.4 m (34 ft)
Max. depth 56.4 m (185 ft)
Surface elevation 1,100 m (3,600 ft)
References St. Mary Reservoir

St. Mary Reservoir is a reservoir in southwestern Alberta, Canada. It was created for irrigation purposes by the damming of the St. Mary River, which was completed in 1951. The Kainai Nation's Blood 148 Indian reserve borders its northwest side. There are camping and picnic areas at the reservoir, and it is a popular site for power boating, water skiing, windsurfing, swimming and fishing.[1]

In 1998 St. Mary Reservoir became an important site for late Pleistocene to early Holocene paleontology and archaeology when it was partially drained for the construction of a new spillway. Flooding of the reservoir had killed the vegetation and when the water level dropped, wind erosion removed layers of unprotected sand and silt, exposing trackways and bones of extinct mammals, as well as stone tools used by Paleoindian hunters.[2]


Based on radiocarbon dating of faunal remains, the assemblage preserved at St. Mary Reservoir were dated from about 11 000 years ago (11 to 11.35 kiloanna (ka) before present (B.P.)). This placed it in latest Pleistocene to earliest Holocene time.[2] Re-examined in 2015, the dating for the camel, horse, and muskox bones subsequently changed this figure to 13.1 - 13.3 ka B.P.[3]


Eleven thousand years ago the Laurentide ice sheet had recently retreated from the area and the site was a windswept, semi-arid plain covered with grasses and low shrubby vegetation, similar to the mammoth steppes of Europe and Asia. The rich open grassland and the reliable supply of water at the river supported herds of large, late Pleistocene mammals and other animals.[2]


The fossil assemblage includes skeletal remains of the extinct horse Equus conversidens, the extinct musk ox Bootherium bombifrons, the extinct bison Bison antiquus, the extant caribou Rangifer tarandus, the extant badger Taxidea taxus and other mustelids, as well as canids and ground squirrels.

Footprints and trackways preserved in silt include those of the extinct elephant Mammuthus primigenius and the extinct camel Camelops hesternus, in addition to those of horse, bison and caribou. Some of the trackways show evidence of browsing, herding, and social interaction.[2]


The herds of animals and the reliable supply of water attracted Paleoindian hunters, and the artifacts recovered from the site suggest that it was a hunting locality. Most of the material consists of stone flakes and flake fragments. A stone chopper, a biface fragment and a few flake tools have been found associated with remains of horse and musk ox.[2] There are also Clovis points with preserved residue of horse and bison protein.[4]


  1. ^ Anonymous. "Atlas of Alberta Lakes". Retrieved 2014-02-01. 
  2. ^ a b c d e McNeil, P., Hills, L.V., Kooyman, B. and Tolman, S. (2004). Late Pleistocene geology and fauna of the Wally's Beach site (DhPg-8), Alberta, Canada. In: J.H. Kelley and B. Kooyman, editors, Archeology on the edge: New perspectives from the northern Plains. University of Calgary Press, 270 p.
  3. ^ Michael R. Waters; Thomas W. Stafford Jr.; Brian Kooyman; L. V. Hills (March 23, 2015). "Late Pleistocene horse and camel hunting at the southern margin of the ice-free corridor: Reassessing the age of Wally's Beach, Canada". PNAS. doi:10.1073/pnas.1420650112. 
  4. ^ Kooyman, B., Newman, M.E, Cluney, C., Lobb, M., Tolman, S., McNeil, P. and Hills, L.V. (2001). Identification of horse exploitation by Clovis hunters based on protein analysis. American Antiquity 66(4): 686-691.