West Elk Mountains

The West Elk Mountains are a high mountain range in the west-central part of the U.S. state of Colorado. They lie primarily within the Gunnison National Forest, and part of the range is protected as the West Elk Wilderness. The range is primarily located in Gunnison County, with small parts in eastern Delta and Montrose counties.

West Elk Mountains
Whetstone Mountain in the West Elk Mountains
Highest point
PeakWest Elk Peak
Elevation13,042 ft (3,975 m)
Coordinates38°43′05″N 107°11′57″W
Geography
CountryUnited States
StateColorado
CountiesGunnison, Delta and Montrose
Parent rangeRocky Mountains
Borders onElk Mountains

The West Elks are surrounded by tributaries of the Gunnison River. The range is bounded on the north by the North Fork of the Gunnison and on the east by the East River, another tributary of the Gunnison. On the south and west it is contiguous with Black Mesa and Fruitland Mesa, both part of the uplift in which sits the Black Canyon of the Gunnison. On the northeast it is contiguous with the Elk Mountains, being separated from them by Anthracite Creek and Coal Creek. Nearby towns include Gunnison, Paonia, and the ski resort of Crested Butte.

Geology

The northern and southern West Elk Mountains have contrasting geologic histories and surface features. In the north, the prominent peaks are laccoliths, formed when magma intruded into Mancos Shale about 30 million years go. Since then, the overlying Mesozoic sedimentary rock, including the relatively soft Mancos Shale, has eroded away, exposing the laccoliths. Laccoliths in the West Elk Mountains include Marcellina Mountain, Mount Gunnison, East Beckwith Mountain, the Anthracite Range, Mount Axtell, Carbon Peak, and Whetstone Mountain.[1][2]

In contrast, volcanic rocks dominate the southern portion of the range. Shortly after the laccolith intrusions in the north, volcanic activity began to the south. A large stratovolcano and other vents ejected material that accumulated over what is now the southern West Elk Mountains. Most of these volcanic rocks are included in the West Elk Breccia Formation, a heterogeneous collection of volcanic materials including extensive mudflow deposits. West Elk Breccia is in places over 3,500 feet (1,100 m) thick.[1][2][3]

On top of the West Elk Breccia, volcanic ash was deposited through repeated eruptions in the San Juan volcanic field to the south. Most of the ash was deposited 26 to 27 million years ago. The resulting rock, tuff, is relatively soft, but the ash landing toward the southern edge of the West Elk volcanic field was hot enough to fuse into harder welded tuff. These welded tuffs are more resistant to weathering than the underlying breccia and today they cap multiple south-sloping mesas in the southern West Elk Mountains.[1][2][3]

Erosion has cut valleys and defined the mesas and peaks we see today. The highest point in the West Elk Mountains is West Elk Peak, which is located near the center of the large volcano that once dominated this landscape. Stratigraphic profiles of these rock layers can be seen at the southern edge of the West Elk Mountains where the Gunnison River has eroded through the volcanic strata. A good example can be seen at the Dillion Pinnacles in Curecanti National Recreation Area. The resistant welded tuff that caps Dillon Mesa is on top, overlying the West Elk Breccia, which has eroded into the pinnacles. Exposed under the breccia are the older, underlying Mesozoic sedimentary rocks including the Mancos, Dakota, and Morrison Formations.[1]

Prominent peaks
2013 aerial photo
The 9 Peaks of the West Elk Mountains With At Least 500 Meters of Topographic Prominence
Rank Mountain Peak Elevation Prominence Isolation
1 West Elk Peak NGS PB 3975.200 = 13,042 feet
3975 m		 0943.356 = 3,095 feet
943 m		 00022.18 = 13.8 miles
22.2 km
2 Mount Gunnison NGS PB 3878.700 = 12,725 feet
3879 m		 1081.735 = 3,549 feet
1082 m		 00019.05 = 11.8 miles
19.1 km
3 Whetstone Mountain NGS PB 3818.100 = 12,527 feet
3818 m		 0748.589 = 2,456 feet
749 m		 00015.11 = 9.4 miles
15.1 km
4 East Beckwith Mountain NGS PB 3792.100 = 12,441 feet
3792 m		 0759.562 = 2,492 feet
760 m		 00011.01 = 6.8 miles
11.0 km
5 Anthracite Range High Point NGS PB 3777.800 = 12,394 feet
3778 m		 0647.700 = 2,125 feet
648 m		 00007.68 = 4.8 miles
7.7 km
6 Carbon Peak NGS PB 3684.300 = 12,088 feet
3684 m		 0664.159 = 2,179 feet
664 m		 00006.31 = 3.9 miles
6.3 km
7 Mount Guero NGS PB 3675.400 = 12,058 feet
3675 m		 0741.274 = 2,432 feet
741 m		 00010.27 = 6.4 miles
10.3 km
8 Coal Mountain[4] PB 3460.528 = 11,710 feet
3570 m		 0831.494 = 1,715 feet
523 m		 00008.18 = 4.8 miles
7.8 km
9 Marcellina Mountain[4] PB 3460.528 = 11,353 feet
3461 m		 0831.494 = 2,728 feet
831 m		 00008.18 = 5.1 miles
8.2 km

See also

References
  1. Prather, Thomas (1999). Geology of the Gunnison Country (2nd ed.). Gunnison, Colorado: B&B Printers. LCCN 82-177244.
  2. Streufert, Randall (1999). RS-37 Geology and Mineral Resources of Gunnison County, Colorado (PDF). Denver, Colorado: Colorado Geological Survey. Retrieved 18 November 2017.
  3. Gaskill, D. L.; Mutschler, F. E.; Bartleson, B. L. (1981). "West Elk volcanic field, Gunnison and Delta counties, Colorado" (PDF). In Epis, R. C.; Callender, J. F. (eds.). Western Slope (Western Colorado), New Mexico Geological Society 32nd Annual Fall Field Conference Guidebook. pp. 305–316. Retrieved 18 November 2017.
  4. The elevation of this summit has been converted from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). National Geodetic Survey
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