# Little Iskut Formation

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Geological formation in British Columbia

Little Iskut Formation Stratigraphic range: 7.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N Paleogeological map of the Little Iskut Formation at the end of the Little Iskut eruptive period Type Geological formation[1] Unit of Mount Edziza volcanic complex[2] Sub-units Upper Little Iskut[1] Lower Little Iskut[1] Underlies Armadillo Formation[1] Nido Formation[1] Overlies Raspberry Formation[1] Lithology Primary Trachybasalt[1] Location Coordinates 57°30′N 130°36′W / 57.5°N 130.6°W / 57.5; -130.6[2] Region British Columbia[1] Country Canada[1] Type section Named for Little Iskut River[1] Named by Souther et al.[3] Year defined 1984[3]

The **Little Iskut Formation** is a [stratigraphic unit](/source/Stratigraphic_unit) of [Miocene](/source/Miocene) age in northwestern [British Columbia](/source/British_Columbia), Canada.

## Naming

The Little Iskut Formation takes its name from the [Little Iskut River](/source/Little_Iskut_River), a [tributary](/source/Tributary) of the [Iskut River](/source/Iskut_River) which flows southeast from the southern end of the [Mount Edziza volcanic complex](/source/Mount_Edziza_volcanic_complex).[1][4]

## Geology

The Little Iskut Formation has a volume of 14.6 km3 (3.5 mi3), making it the seventh most voluminous [geological formation](/source/Geological_formation) comprising the Mount Edziza volcanic complex.[1][2] It occurs at the northeastern end of the [Spectrum Range](/source/Spectrum_Range) where it covers a roughly 10-kilometre-wide (6.2-mile) area. A small portion of the Little Iskut Formation is exposed in the [Mess Creek Escarpment](/source/Mess_Creek_Escarpment) to the west.[1]

The Little Iskut Formation consists of [trachybasalt](/source/Trachybasalt) flows and [breccia](/source/Breccia). It ranges in thickness from 90 m (300 ft) on Stewpot Ridge to about 300 m (980 ft) near the middle of Artifact Ridge. The Little Iskut Formation originally formed a small symmetrical [shield volcano](/source/Shield_volcano) during the Miocene.[1]

The Little Iskut Formation conformably overlies the [Raspberry Formation](/source/Raspberry_Formation) south of [Bourgeaux Creek](/source/Bourgeaux_Creek). Little Iskut trachybasalt is overlain by [rhyolite](/source/Rhyolite) of the [Armadillo Formation](/source/Armadillo_Formation) and [basalt](/source/Basalt) of the Nido Formation. Two subunits comprise the Little Iskut Formation; the upper unit consists entirely of trachybasalt lava flows while the lower unit consists of abundant breccia.[1]

[K–Ar dating](/source/K%E2%80%93Ar_dating) has yielded an age of 7.2 ± 0.3 million years for Little Iskut trachybasalt.[1]

## See also

- [Volcanism of the Mount Edziza volcanic complex](/source/Volcanism_of_the_Mount_Edziza_volcanic_complex)

## References

1. ^ [***a***](#cite_ref-Souther_1-0) [***b***](#cite_ref-Souther_1-1) [***c***](#cite_ref-Souther_1-2) [***d***](#cite_ref-Souther_1-3) [***e***](#cite_ref-Souther_1-4) [***f***](#cite_ref-Souther_1-5) [***g***](#cite_ref-Souther_1-6) [***h***](#cite_ref-Souther_1-7) [***i***](#cite_ref-Souther_1-8) [***j***](#cite_ref-Souther_1-9) [***k***](#cite_ref-Souther_1-10) [***l***](#cite_ref-Souther_1-11) [***m***](#cite_ref-Souther_1-12) [***n***](#cite_ref-Souther_1-13) [***o***](#cite_ref-Souther_1-14) [***p***](#cite_ref-Souther_1-15) [Souther, J. G.](/source/Jack_Souther) (1992). The Late Cenozoic Mount Edziza Volcanic Complex, British Columbia. *[Geological Survey of Canada](/source/Geological_Survey_of_Canada)* (Report). Memoir 420. Canada Communication Group. pp. 32, 47, 61, 63, 246, 249, 267. [doi](/source/Doi_(identifier)):[10.4095/133497](https://doi.org/10.4095%2F133497). [ISBN](/source/ISBN_(identifier)) [0-660-14407-7](https://en.wikipedia.org/wiki/Special:BookSources/0-660-14407-7).

1. ^ [***a***](#cite_ref-Edwards_2-0) [***b***](#cite_ref-Edwards_2-1) [***c***](#cite_ref-Edwards_2-2) Edwards, Benjamin Ralph (1997). *Field, kinetic, and thermodynamic studies of magmatic assimilation in the Northern Cordilleran Volcanic Province, northwestern British Columbia* (PhD thesis). [University of British Columbia](/source/University_of_British_Columbia). p. 10. [ISBN](/source/ISBN_(identifier)) [0-612-25005-9](https://en.wikipedia.org/wiki/Special:BookSources/0-612-25005-9).

1. ^ [***a***](#cite_ref-LCGU_3-0) [***b***](#cite_ref-LCGU_3-1) ["Little Iskut Formation"](https://weblex.canada.ca/html/008000/GSCC00053008550.html). *[Lexicon of Canadian Geologic Units](/source/Lexicon_of_Canadian_Geologic_Units)*. [Government of Canada](/source/Government_of_Canada). Retrieved 2023-08-04.

1. **[^](#cite_ref-4)** ["Little Iskut River"](https://web.archive.org/web/20211024202848/https://apps.gov.bc.ca/pub/bcgnws/names/2478.html). *[BC Geographical Names](/source/BC_Geographical_Names)*. Government of British Columbia – B.C. Geographical Names Office (BCGNO). Archived from [the original](https://apps.gov.bc.ca/pub/bcgnws/names/2478.html) on 2021-10-24. Retrieved 2023-06-27.

v t e Mount Edziza volcanic complex Cinder cones The Ash Pit Cache Hill Camp Hill Cinder Cliff Cocoa Crater Coffee Crater Eve Cone Exile Hill Icefall Cone Kana Cone Keda Cone Klastline Cone Mess Lake Cone Moraine Cone Nahta Cone Outcast Hill Ridge Cone Sidas Cone Sleet Cone Source Hill Storm Cone Thaw Hill Triplex Cones Twin Cone Walkout Creek centres Williams Cone Subglacial volcanoes Pillow Ridge Tennena Cone Tsekone Ridge Wetalth Ridge Central volcanoes Armadillo Peak Mount Edziza Ice Peak Spectrum Range Lava domes Glacier Dome IGC Centre Nanook Dome Pharaoh Dome The Pyramid Sphinx Dome Triangle Dome Lava fields Desolation Lava Field Mess Lake Lava Field Snowshoe Lava Field Plateaus Arctic Lake Plateau Big Raven Plateau Kitsu Plateau Ridges Artifact Ridge Cartoona Ridge Idiji Ridge Obsidian Ridge Pillow Ridge Sorcery Ridge Tsekone Ridge Wetalth Ridge Yagi Ridge Mountain passes Destell Pass Raspberry Pass Bluffs Koosick Bluff Ornostay Bluff Glaciers Idiji Glacier Tenchen Glacier Tencho Glacier Tennaya Glacier Streams Artifact Creek Ball Creek Bourgeaux Creek Chakima Creek Crayke Creek Elwyn Creek Flyin Creek Gerlib Creek Kadeya Creek Kitsu Creek Little Iskut River More Creek Nagha Creek Nido Creek Pyramid Creek Raspberry Creek Sezill Creek Shaman Creek Sorcery Creek Stewbomb Creek Tadekho Creek Taweh Creek Tenchen Creek Tennaya Creek Tsecha Creek Walkout Creek Stratigraphic units Armadillo Formation Big Raven Formation (Sheep Track Member) Edziza Formation Ice Peak Formation Kakiddi Formation Klastline Formation Little Iskut Formation Nido Formation (Tenchen Member) Pyramid Formation Raspberry Formation Other Cartoona Peak Gnu Butte Mess Creek Escarpment Volcanism of the Mount Edziza volcanic complex

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Adapted from the Wikipedia article [Little Iskut Formation](https://en.wikipedia.org/wiki/Little_Iskut_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Little_Iskut_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.