Crevasse Crag is a jagged steep-sided prominence on the summit of a glaciated mountain ridge in the

Lillooet Ranges The Lillooet Ranges are the southeasternmost subdivision of the Pacific Ranges of the Coast Mountains of British Columbia. They are located between the drainage of the Lillooet River and Harrison Lake on the west and the canyon of the Fraser Rive ...

of southwestern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

, Canada. It is located about southeast of the village of Pemberton. Situated on the boundary between

New Westminster Land District The New Westminster Land District is one of 59 land districts of British Columbia, Canada, which are the underlying cadastral divisions of that province, created with rest of those on Mainland British Columbia via the ''Lands Act'' of the Colony ...

and Kamloops Division Yale Land District, the peak has a maximum elevation of and a

topographic prominence In topography, prominence (also referred to as autonomous height, relative height, and shoulder drop in US English, and drop or relative height in British English) measures the height of a mountain or hill's summit relative to the lowest contou ...

of . The name of the peak was adopted on March 31, 1969 as submitted by climber Christian Adam. It is named after the large crevasse directly below its north ridge. Prior to its adoption in 1969, Crevasse Crag was climbed by Adam et al. on August 16, 1967. Technically, Crevasse Crag is the remains of an extinct volcano that formed during the onset of Pemberton Belt

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called a ...

16 million years ago. This activity produced

breccia Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of ...

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...

s and

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more pro ...

- phyric flows, all of which form the present day edifice of Crevasse Crag. Analyses of major, trace and

rare-earth element The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides ( yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silv ...

s indicate that

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite ...

andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predo ...

and

basaltic andesite Basaltic andesite is a volcanic rock that is intermediate in composition between basalt and andesite. It is composed predominantly of augite and plagioclase. Basaltic andesite can be found in volcanoes around the world, including in Central Amer ...

lava flows form its lower flanks. These overlie

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

and younger intrusive rocks that form the glaciated mountain ridge on which Crevasse Crag lies.

References

External links

* Volcanoes of British Columbia Two-thousanders of British Columbia Pemberton Volcanic Belt Subduction volcanoes Miocene volcanoes Extinct volcanoes Lillooet Ranges Polygenetic volcanoes New Westminster Land District Kamloops Division Yale Land District {{BritishColumbiaCoast-geo-stub