Cochetopa Dome is a mountain in the

San Juan Mountains The San Juan Mountains is a high and rugged mountain range in the Rocky Mountains in southwestern Colorado and northwestern New Mexico. The area is highly mineralized (the Colorado Mineral Belt) and figured in the gold and silver mining industry ...

, in

Saguache County Saguache County (suh-WATCH ) is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 6,368. The county seat is Saguache. History Saguache County was formed December 29, 1866 in the Territory of Colorado wh ...

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

. The mountain is located in the

Gunnison National Forest The Gunnison National Forest is a U.S. National Forest covering 1,672,136 acres (2,612.71 sq mi, or 6,766.89 km²) rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on ...

, extruded into the Cochetopa

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

approximately 27 million years ago. The Chochetopa caldera is one of over a dozen such collapsed volcanoes within the

San Juan volcanic field The San Juan volcanic field is part of the San Juan Mountains in southwestern Colorado. It consists mainly of volcanic rocks that form the largest remnant of a major composite volcanic field that covered most of the southern Rocky Mountains in t ...

. The caldera is approximately wide and vertical subsidence was up to . The Cochetopa caldera, with Cochetopa Dome within it, is one of the most recognizable of the calderas in the region. Helping preserve the structure of this particular caldera is that its development was more recent than many of the larger calderas elsewhere in the San Juan Mountains, thus there was less regional volcanism to disrupt the caldera's structure. Also, the caldera was only modestly filled with post-subsidence sediments and much of this was weaker,

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 cont ...

aceaus deposits, which have been more readily eroded from the caldera floor. And lastly, the caldera is drained through Cochetopa Canyon where hard,

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

has limited down cutting and erosion of the caldera. The present vegetation helps make the caldera's features and extent even more apparent. The floor of the caldera is dominated by grass and shrublands while the caldera rim and the interior lava dome (Cochetopa Dome) are forested. This contrast in vegetation helps a visitor visualize the caldera

Hiking

Private property to the north and west limits access to the mountain. The summit can be reached on public land from the southeast. From the Cochetopa Park Spur F Road (Forest Road 804.1F), at an open saddle at an elevation of (), the summit is a , class-2 hike through meadow and forest. The elevation gain is .Forest road information is available a
Colorado Trail Explorer
Off-trail distances can also be computed. Accessed 8 April 2021

References

External links

* {{Colorado San Juan Mountains (Colorado) Mountains of Saguache County, Colorado Gunnison National Forest Mountains of Colorado Volcanoes of Colorado Calderas of Colorado

Hiking

See also

References

External links