Ellis Group#Subdivisions

{{Short description|Geological group in Alberta, Canada and Montana, U.S.}}

{{distinguish|Ellis Bay Formation}}

{{Infobox rockunit

| name = Ellis Group

| image =

| caption =

| type = Geological group

| age = {{Fossil range|Bajocian|Oxfordian|Bajocian-Oxfordian}}

| period = Oxfordian

| prilithology = Shale, sandstone

| otherlithology = Siltstone, limestone

| namedfor = Fort Ellis

| namedby = A.C. Peale

| year_ts = 1893

| region = Alberta, Saskatchewan, Montana, Wyoming

| country = Canada, United States

| coordinates = {{coord|48.0|N|108.6|W|display=inline,title}}

| paleocoordinates = {{coord|40.9|N|49.2|W|display=inline}}

| unitof =

| subunits = Swift, Rierdon, Piper & Sawtooth Formations

| underlies = Mannville Group

| overlies = Rundle Group & Shaunavon Formation

| thickness = up to {{convert|150|m|ft|abbr=on}}

| extent = WCSB

| area =

| map = {{Location map+ | Canada

| relief = 1

| width = 250

| float = center

| places =

{{Location map~ | Canada

| lat_deg = 48.0

| lon_deg = -108.6

| mark = Blue pog.svg

| marksize = 12

}}

}}

| map_caption =

}}

File:Piper Formation Wyoming.jpg bed in the Piper Formation, Big Horn Basin of Wyoming.]]

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.Peale, A.C., 1893. The Paleozoic section in the vicinity of Three Forks, Montana. United States Geological Survey, Bulletin 110, p.9-56.

Lithology

The Ellis Group is composed of shale and sandstones deposited in a marine and transitional environment.

{{Cite web

|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:004590

|archive-url=https://archive.today/20130221102359/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:004590

|url-status=dead

|archive-date=2013-02-21

|title=Ellis Group

|author=Lexicon of Canadian Geologic Units

|access-date=2010-01-01

}}

= 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 {{convert|80|m|ft|-1}}, but thickens on either side of the Sweetgrass Arch and reaches up to {{convert|150|m|ft|-1}} in southeastern Alberta.

Subdivisions

The Ellis Group includes the following formations, from top to bottom:

class="wikitable"
Sub-unitAgeLithologyMax.
Thickness
Notes
Swift FormationOxfordianmarine shale, transitional shale, siltstone and sandstone{{convert|41|m|ft
1|abbr=on}}

| {{center|{{Cite web|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:014827 |archive-url=https://archive.today/20120709083920/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:014827 |url-status=dead |archive-date=2012-07-09 |title=Swift Formation |author=Lexicon of Canadian Geologic Units |access-date=2010-01-03 }}}}

Rierdon FormationBathonian to Callovianmarine shale and limestone{{convert|60|m|ft
1|abbr=on}}

| {{center|{{Cite web|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:012780 |archive-url=https://archive.today/20120707024906/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:012780 |url-status=dead |archive-date=2012-07-07 |title=Rierdon Formation |author=Lexicon of Canadian Geologic Units |access-date=2010-01-03 }}}}

Sawtooth FormationBajocian to Bathonianquartzose sandstone with shale{{convert|41|m|ft
1|abbr=on}}

| {{center|{{Cite web|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:013351 |archive-url=https://archive.today/20120707084855/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:013351 |url-status=dead |archive-date=2012-07-07 |title=Sawtooth Formation |author=Lexicon of Canadian Geologic Units |access-date=2010-01-03 }}}}

Piper FormationMiddle Jurassicsandy limestone (top)
papery shale
siltstone and shale
grey limestone
white gypsum (base)
{{convert|23|m|ft
1|abbr=on}}

| {{center|{{Cite web|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:011900 |archive-url=https://archive.today/20120708224430/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:011900 |url-status=dead |archive-date=2012-07-08 |title=Piper Formation |author=Lexicon of Canadian Geologic Units |access-date=2010-01-03 }}}}

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.

References