Ravenscrag Formation
| Ravenscrag Formation Stratigraphic range: Paleocene |
|
|---|---|
| Type | Geological formation |
| Sub-units | Upper Ravenscrag Lower Ravenscrag |
| Underlies | Swift Current Formation |
| Overlies | Frenchman Formation |
| Thickness | up to 244 metres (800 ft) |
| Lithology | |
| Primary | Claystone, mudstone, siltstone |
| Other | Sandstone, coal |
| Location | |
| Coordinates | 49°30′07″N 108°58′33″W / 49.50182°N 108.97585°WCoordinates: 49°30′07″N 108°58′33″W / 49.50182°N 108.97585°W |
| Region | Western Canada Sedimentary Basin |
| Country |
 Canada
|
| Type section | |
| Named for | Ravenscrag, Saskatchewan |
| Named by | N.B. Davis, 1918 |
The Ravenscrag Formation is a stratigraphic unit of early Paleocene age in the Western Canada Sedimentary Basin. It takes the name from the settlement of Ravenscrag, Saskatchewan, and was first described in outcrop at Ravenscrag Butte near Frenchman River by N.B. Davis in 1918.
The Ravenscrag Formation is an eastward-thickening wedge of sediments. It is composed primarily of buff, grey and white silty claystone, with mudstone, siltstone, sandstone, and it includes several significant coal seams. These sediments were deposited in floodplain, overbank and swamp environments.
The Ravenscrag Formation is of early Paleocene age and the base of the formation coincides with the Cretaceous-Paleogene boundary, as evidenced by biostratigraphic changes and, in some places, the presence of the terminal Cretaceous iridium anomaly.
The Ravenscrag Formation reaches a maximum thickness of 244 metres (800 ft) and is present in southwestern Saskatchewan and the Cypress Hills area of southeastern Alberta.
Although some early workers included the underlying Frenchman Formation as the lower Ravenscrag, the two are separated by the Cretaceous-Paleogene boundary and are now treated separately. The contact is abrupt but conformable, and occurs at the base of the lowermost coal seam (the No. 1 or Ferris coal seam) in the Ravenscrag Formation.
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