Ellis Group | |
---|---|
Stratigraphic range: | |
Type | Geological group |
Sub-units | Swift, Rierdon, Piper & Sawtooth Formations |
Underlies | Mannville Group |
Overlies | Rundle Group & Shaunavon Formation |
Thickness | up to 150 m (490 ft) [1] |
Lithology | |
Primary | Shale, sandstone |
Other | Siltstone, limestone |
Location | |
Coordinates | 48°00′N108°36′W / 48.0°N 108.6°W |
Approximate paleocoordinates | 40°54′N49°12′W / 40.9°N 49.2°W |
Region | Alberta, Saskatchewan Montana, Wyoming |
Country | Canada United States |
Extent | WCSB |
Type section | |
Named for | Fort Ellis |
Named by | A.C. Peale |
Year defined | 1893 |
The Ellis Group is a stratigraphical unit of Bajocian-Oxfordian age in Alberta, Saskatchewan, Montana and Wyoming in the Western Canadian Sedimentary Basin. It takes the name from Fort Ellis, Montana, and was first described in outcrop in the Rocky Creek Canyon by A.C. Peale in 1893. [2]
The Ellis Group is composed of shale and sandstones deposited in a marine and transitional environment. [1]
Oil is produced from the Sawtooth Formation in southeastern Alberta.
The Ellis Group laterally occurs in the subsurface in southern Alberta and northern and central Montana. [1] It is typically 80 metres (260 ft), but thickens on either side of the Sweetgrass Arch and reaches up to 150 metres (490 ft) in southeastern Alberta.
The Ellis Group includes the following formations, from top to bottom:
Sub-unit | Age | Lithology | Max. Thickness | Notes |
---|---|---|---|---|
Swift Formation | Oxfordian | marine shale, transitional shale, siltstone and sandstone | 41 m (130 ft) | |
Rierdon Formation | Bathonian to Callovian | marine shale and limestone | 60 m (200 ft) | |
Sawtooth Formation | Bajocian to Bathonian | quartzose sandstone with shale | 41 m (130 ft) | |
Piper Formation | Middle Jurassic | sandy limestone (top) papery shale siltstone and shale grey limestone white gypsum (base) | 23 m (80 ft) | |
The Ellis Group is unconformably overlain by the shales and sandstones of the Mannville Group and rests on the carbonates of the Rundle Group. It grades westwards to the shales of the Fernie Group, and eastwards to the shale, sandstones and limestones of the Vanguard and Shaunavon Formations. [1]
The Madison Limestone is a thick sequence of mostly carbonate rocks of Mississippian age in the Rocky Mountain and Great Plains areas of the western United States. The rocks serve as an important aquifer as well as an oil reservoir in places. The Madison and its equivalent strata extend from the Black Hills of western South Dakota to western Montana and eastern Idaho, and from the Canada–United States border to western Colorado and the Grand Canyon of Arizona.
The Belly River Group is a stratigraphical unit of Late Cretaceous age in the Western Canadian Sedimentary Basin.
The Kiskatinaw Formation is a stratigraphical unit of Mississippian age in the Western Canadian Sedimentary Basin.
The Fernie Formation is a stratigraphic unit of Jurassic age. It is present in the western part of the Western Canada Sedimentary Basin in western Alberta and northeastern British Columbia. It takes its name from the town of Fernie, British Columbia, and was first defined by W.W. Leach in 1914.
The Fort St. John Group is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin. It takes the name from the city of Fort St. John, British Columbia and was first defined by George Mercer Dawson in 1881.
The Peace River Formation is a stratigraphical unit of middle Albian age in the Western Canadian Sedimentary Basin.
Colorado is a geologic name applied to certain rocks of Cretaceous age in the North America, particularly in the western Great Plains. This name was originally applied to classify a group of specific marine formations of shale and chalk known for their importance in Eastern Colorado. The surface outcrop of this group produces distinctive landforms bordering the Great Plains and it is a significant feature of the subsurface of the Denver Basin and the Western Canadian Sedimentary Basin. These formations record important sequences of the Western Interior Seaway, and as the geology of this seaway was studied, this name came to be used in states beyond Colorado, but was later replaced in several of these states with more localized names.
The Mannville Group is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin.
The Alberta Group is a stratigraphical unit of Cenomanian to early Campanian age in the Lewis overthrust in the Western Canadian Sedimentary Basin.
The Exshaw Formation is a stratigraphic unit in the Western Canada Sedimentary Basin. It takes the name from the hamlet of Exshaw, Alberta in the Canadian Rockies, and was first described from outcrops on the banks of Jura Creek north of Exshaw by P.S. Warren in 1937. The formation is of Late Devonian to Early Mississippian age as determined by conodont biostratigraphy, and it straddles the Devonian-Carboniferous boundary.
The Woodbend Group is a stratigraphical unit of Frasnian age in the Western Canadian Sedimentary Basin.
Within the earth science of geology, the Edmonton Group is a Late Cretaceous 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 Three Forks Group is a stratigraphical unit of Famennian age in the Williston Basin.
The Shaunavon Formation is a stratigraphical unit of Bathonian age in the Western Canadian Sedimentary Basin.
The Kotaneelee Formation is a stratigraphical unit of Late Cretaceous age in the Western Canadian Sedimentary Basin.
The Ishbel Group is a stratigraphic unit of Permian age in the Western Canadian Sedimentary Basin. It is present in the Canadian Rockies of Alberta and British Columbia. First defined by A. McGugan in 1963, it is named for Mount Ishbel of the Sawback Range in Banff National Park, and parts of the group were first described in the vicinity of the mountain at Ranger Canyon and Johnston Canyon.
The Vanguard Formation is a stratigraphical unit of Callovian to Oxfordian age in the Western Canadian Sedimentary Basin.
The Manitoba Group is a stratigraphical unit of middle to late Devonian age in the Western Canadian Sedimentary Basin.
The Gravelbourg Formation is a stratigraphical unit of Bajocian age in the Western Canadian Sedimentary Basin.
The Elk Formation is a stratigraphic unit of the Western Canada Sedimentary Basin that is present in southeastern British Columbia and southwestern Alberta. It is probably of Early Cretaceous age, but in some areas its strata could be as old as Late Jurassic. It includes minor thin coal beds and was named for outcrops near the now-abandoned Elk River coal mine east of Fernie, British Columbia.