# Pyramid Formation (British Columbia)

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Pyramid_Formation_(British_Columbia)
> Markdown URL: https://mediated.wiki/source/Pyramid_Formation_(British_Columbia).md
> Source: https://en.wikipedia.org/wiki/Pyramid_Formation_(British_Columbia)
> Source revision: 1285486139
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Geological formation in British Columbia

Pyramid Formation Stratigraphic range: 1.2–0.9 Ma PreꞒ Ꞓ O S D C P T J K Pg N The Pyramid consists of Pyramid Formation trachyte Type Geological formation[1] Unit of Mount Edziza volcanic complex[2] Underlies Ice Peak Formation, Edziza Formation[1] Overlies Nido Formation[1] Lithology Primary Trachyte, comendite, pantellerite[1] Other Basalt[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 The Pyramid[1] Named by Souther et al.[3] Year defined 1984[3] Cross section showing the maximum extent of the Pyramid Formation at the end of Pyramid time

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

## Name

The Pyramid Formation takes its name from [The Pyramid](/source/The_Pyramid_(British_Columbia)), a prominent [pyramid](/source/Pyramid)-shaped [lava dome](/source/Lava_dome) on the northeastern flank of [Mount Edziza](/source/Mount_Edziza).[1][4]

## Geology

Two subunits comprise the Pyramid Formation. The lower unit is a basal [pyroclastic](/source/Pyroclastic_rock) [member](/source/Member_(geology)) up to 3 m (9.8 ft) thick. It contains [trachytic](/source/Trachytic) [pumice](/source/Pumice), sodic [pyroxene](/source/Pyroxene) and [alkali feldspar](/source/Alkali_feldspar); the latter two are present in the form of [lithic](/source/Lithic_fragment_(geology)) [clasts](/source/Clast) and crystals. This unit is rusty brown in colour and was deposited by a [pyroclastic surge](/source/Pyroclastic_surge). The upper unit consists of a [basalt](/source/Basalt) member up to 65 m (213 ft) thick. It includes 6 to 10 individual basalt flows that reach thicknesses of 3–20 m (9.8–65.6 ft). They appear to have been deposited almost immediately after the pyroclastic surge was erupted.[1] Several silicic lava domes and minor lava flows of the Pyramid Formation postdate the basalt member. Among the silicic domes are [Sphinx Dome](/source/Sphinx_Dome), [Pharaoh Dome](/source/Pharaoh_Dome) and The Pyramid.[5]

The Pyramid Formation has a volume of 11.4 km3 (2.7 mi3), making it the eighth most voluminous [geological formation](/source/Geological_formation) of the [Mount Edziza volcanic complex](/source/Mount_Edziza_volcanic_complex) after the [Little Iskut Formation](/source/Little_Iskut_Formation).[1][2] It overlies the [Nido Formation](/source/Nido_Formation) and underlies the [Ice Peak](/source/Ice_Peak_Formation) and [Edziza](/source/Edziza_Formation) formations, all of which have formed in the last 8 million years. [K–Ar dating](/source/K%E2%80%93Ar_dating) of the Pyramid Formation has yielded ages of 1.2 ± 0.4 million years and 1.20 ± 0.03 million years for [comenditic](/source/Comenditic) [glass](/source/Volcanic_glass) and 0.94 ± 0.12 million years and 0.94 ± 0.05 million years for trachyte.[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) [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. 100, 129, 132, 133, 134, 246, 248, 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) ["Pyramid Formation"](https://weblex.canada.ca/html/012000/GSCC00053012294.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-BCGN_4-0)** ["The Pyramid"](https://apps.gov.bc.ca/pub/bcgnws/names/22196.html). *[BC Geographical Names](/source/BC_Geographical_Names)*. Government of British Columbia – B.C. Geographical Names Office (BCGNO). Retrieved 2023-07-02.

1. **[^](#cite_ref-5)** Smellie, John L.; Edwards, Benjamin R. (2016). *Glaciovolcanism on Earth and Mars: Products, Processes and Palaeoenvironmental Significance*. [Cambridge University Press](/source/Cambridge_University_Press). p. 43. [ISBN](/source/ISBN_(identifier)) [978-1-107-03739-7](https://en.wikipedia.org/wiki/Special:BookSources/978-1-107-03739-7).

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

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