Chipmunk Mountain is a

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...

in southwestern

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

, Canada, located southwest of

Bralorne Bralorne ( ) is a historic Canadian gold mining community in the Bridge River District of British Columbia, some 130 km on dirt roads west of the town of Lillooet Lillooet () is a district municipality in the Squamish-Lillooet region o ...

. It has an elevation of and a

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

of , making it the highest point on an east-trending

scree Scree is a collection of broken rock fragments at the base of a cliff or other steep rocky mass that has accumulated through periodic rockfall. Landforms associated with these materials are often called talus deposits. The term ''scree'' is ap ...

d ridge. This horn-like rocky tower is similar to

The Black Tusk The Black Tusk, known as Q̓elqámtensa ti Skenknápa in the St'at'imcets (Lillooet) language and as T'ákt'akmúten tl'a Ín7inyáx̱a7en in the Sḵwx̱wú7mesh (Squamish) language, is a stratovolcano and a pinnacle of volcanic rock in Garib ...

Garibaldi Provincial Park Garibaldi Provincial Park, also called Garibaldi Park, is a wilderness park located on the coastal mainland of British Columbia, Canada, 70 kilometres (43.5 mi) north of Vancouver. It was established in 1920 and named a Class A Provincial ...

. The mountain was named in 1920 by James Landsborough after a summit party had given lunch scraps to a

chipmunk Chipmunks are small, striped rodents of subtribe Tamiina. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia. Taxonomy and systematics Chipmunks are classified as four genera: '' ...

Geology

Chipmunk Mountain is the remains of an extinct volcano that formed during the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

epoch. The

volcanic rock Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...

s comprising Chipmunk Mountain crop out in a area and consist of

pyroclastic rock Pyroclastic rocks are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroclasts. Pyroclastic rocks are a type of volcaniclastic deposit, which are deposit ...

s, sills and

dikes Dyke or dike may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), formations of magma or sediment that cut through and across the layering of adjacent rocks * Dike (mythology), ''Dikē'', the Greek goddess ...

. These volcanic rocks range from

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

s to

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

s, with the majority classifying as

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 Ameri ...

s and

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 predomina ...

s. They are closely related to the

calc-alkaline The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic ...

volcanic centres of the

Pemberton Volcanic Belt The Pemberton Volcanic Belt is an eroded Oligocene-Miocene volcanic belt at a low angle near the Mount Meager massif, British Columbia, Canada. The Garibaldi and Pemberton volcanic belts appear to merge into a single belt, although the Pemberto ...

, indicating that the volcanic rocks comprising Chipmunk Mountain were created as a result of

volcanism Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of a solid-surface astronomical body such as a planet or a moon. It is caused by the presence of a he ...

in the

Canadian Cascade Arc The Canadian Cascade Arc, also called the Canadian Cascades, is the Canada, Canadian segment of the North American Cascade Volcanic Arc. Located entirely within the Canadian province of British Columbia, it extends from the Cascade Mountains in th ...

. The volcanic rocks have been dated to be million years old, which correlates with the time of Pemberton Belt volcanism.

Gallery

Chipmunk Peak.jpg, Chipmunk Mountain, northeast aspect Chipmunk Mountain summit.jpg, Chipmunk Mountain

References

External links

* *{{cite bivouac, id=1032, title=Chipmunk Mountain, accessdate=2012-09-16 Volcanoes of British Columbia Two-thousanders of British Columbia Pemberton Volcanic Belt Subduction volcanoes Miocene volcanoes Extinct volcanoes of North America Pacific Ranges Polygenetic volcanoes Pemberton Valley

Geology

Gallery

See also

References

External links