Stratigraphic range: Bajocian-Oxfordian
|Overlies||Rundle Group, Shaunavon Formation|
|Thickness||up to 150 metres (490 ft)|
|Named for||Fort Ellis|
|Named by||A.C. Peale, 1893|
The Ellis Group Lateral occurs in the sub-surface in southern Alberta and northern and central Montana. 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 south-eastern Alberta.
The Ellis Group includes the following formations, from top to bottom:
|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)
siltstone and shale
white gypsum (base)
|23 m (80 ft)|||
Relationship to other units
The Ellis Group is unconformably overlain by the shale and sandstone of the Mannville Group and rests on the carbonates of the Rundle Group. It grades westwards to the Fernie Group shale, and eastwards to shale, sandstones and limestone of the Vanguard Formation and Shaunavon Formation.
- Lexicon of Canadian Geologic Units. "Ellis Group". Retrieved 2010-01-01.
- Peale, A.C., 1893. The Paleozoic section in the vicinity of Three Forks, Montana. United States Geological Survey, Bulletin 110, p.9-56.
- Lexicon of Canadian Geologic Units. "Swift Formation". Retrieved 2010-01-03.
- Lexicon of Canadian Geologic Units. "Rierdon Formation". Retrieved 2010-01-03.
- Lexicon of Canadian Geologic Units. "Sawtooth Formation". Retrieved 2010-01-03.
- Lexicon of Canadian Geologic Units. "Piper Formation". Retrieved 2010-01-03.