Ellis Group
geologic group
The Ellis Group is a stratigraphic 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.
Lithology
The Ellis Group is composed of shale and sandstones deposited in a marine and transitional environment.
Hydrocarbon production
Oil is produced from the Sawtooth Formation in southeastern Alberta.
Distribution
The Ellis Group laterally occurs in the subsurface 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 southeastern Alberta.
Subdivisions
The Ellis Group includes the following formations, from top to bottom:
Relationship to other units
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.
The public source identifies “Ellis Group” as geologic group. This brief keeps that definition visible, then builds a research path around Ellis, Group and geologic.
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A short description can identify a subject without explaining its stakes. For “Ellis Group”, the useful work is to connect “geologic group” to the records capable of establishing context and consequence.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Aug 4, 2026. The linked authority identifier is Q5365888. Authority coordinates are 48.000, -108.600. None of the 1 selected statements returned an explicit reference. The first chronological checks are 1893.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Ellis Group” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.