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 ...
summit
A summit is a point on a surface that is higher in elevation than all points immediately adjacent to it. The topographic terms acme, apex, peak (mountain peak), and zenith are synonymous.
The term (mountain top) is generally used only for ...
Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
of
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
Colorado
Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
,
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
Köppen Climate Classification
The Köppen climate classification divides Earth climates into five main climate groups, with each group being divided based on patterns of seasonal precipitation and temperature. The five main groups are ''A'' (tropical), ''B'' (arid), ''C'' (te ...
subtype for Crested Butte is "Dfc" which is continental subarctic. This climate type is dominated by the winter season with a long, bitterly cold period of minimal daylight hours, heavy snowfall and low humidity. The annual snowfall average is with January recording the highest average snowfall at . July is the warmest month with an average temperature of while January is the coldest month with an average temperature of . The average temperature for the year is .Climate Summary for Crested Butte /ref>
butte
In geomorphology, a butte ( ) is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and table (landform), tablelands. The word ''butte'' comes from the French l ...
, formed when
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
intruded into Mancos Shale approximately 30 million years ago. Subsequently the softer, overlying
sedimentary rock
Sedimentary rocks are types of rock (geology), rock formed by the cementation (geology), cementation of sediments—i.e. particles made of minerals (geological detritus) or organic matter (biological detritus)—that have been accumulated or de ...
has eroded away, exposing the more resistant
igneous rock
Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.
The magma can be derived from partial ...
granodiorite
Granodiorite ( ) is a coarse-grained (phaneritic) intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar.
The term banatite is sometimes used informally for various rocks ranging from gra ...
porphyry. The lower slopes consist of Mancos Shale overlain with debris from the
granitic
A granitoid is a broad term referring to a diverse group of coarse-grained igneous rocks that are widely distributed across the globe, covering a significant portion of the Earth's exposed surface and constituting a large part of the continental ...
slopes above. The Mancos Shale at the base of Crested Butte can be an unstable substrate for building and result in geologic hazards such as
landslide
Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...
s and
earthflow
An earthflow (earth flow) is a downslope viscous flow of fine-grained materials that have been saturated with water and moves under the pull of gravity. It is an intermediate type of mass wasting that is between downhill creep and mudflow. The ...
s.
Crested Butte is one of over a dozen laccoliths in the Elk and adjacent West Elk Mountains. The magma intrusions associated with these laccoliths resulted in contact metamorphism of the surrounding sedimentary rock and mineralization. The metamorphism also altered the
bituminous coal
Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the coal seam, ...
present in the sedimentary rock into a higher quality coal, including
anthracite
Anthracite, also known as hard coal and black coal, is a hard, compact variety of coal that has a lustre (mineralogy)#Submetallic lustre, submetallic lustre. It has the highest carbon content, the fewest impurities, and the highest energy densit ...
, which was mined extensively in the Crested Butte area during the late 19th and early 20th centuries.
Gallery
File:View of Meridian Lake and Mount Crested Butte above the Colorado city of Crested Butte on the high, dirt Washington Gulch Road in Gunnison County, Colorado LCCN2015633497.tif, Crested Butte viewed from Meridian Lake
File:Crested Butte.jpg, Crested Butte and the town of Crested Butte
File:Crested Butte geologic cross section USGS 1991.jpg, Geologic cross section of Crested Butte