Laramie Mountains
| Laramie Mountains | |
|---|---|
 The Laramie Mountains (in purple) with the Oregon Trail |
|
 Sherman Granite at Vedauwoo in winter |
|
| Highest peak | Laramie Peak ( 3131 m ) |
| location | Wyoming , Colorado (USA) |
| part of | Rocky mountains |
| Coordinates | 41 ° 38 ′ N , 105 ° 40 ′ W |
The Laramie Mountains ( Eng. "Mountains of Laramie") are a mountain range on the eastern edge of the Rocky Mountains in the US states of Wyoming and Colorado . They were named after the Laramie River , which cuts the mountain range from southwest to northeast and divides it in two.
geography
The Laramie Mountains are the northernmost branch of the chains located on the eastern edge of the southern Rocky Mountains and represent the immediate continuation of the much higher Front Range that adjoins it further south . In their higher elevations, they only average values between 2,400 and 2900 meters above sea level and are therefore lower than the rest of the Rockies. An exception is Laramie Peak with a height of 3131 meters.
Starting from southeastern Wyoming between Cheyenne and Laramie , the Laramie Mountains extend in a north-northwest direction for around 200 kilometers to Casper . This is where the Laramie Mountains end , the mountain range is interrupted by a plain that extends to the Bighorn Mountains further north . This gap between the two mountain ranges was used by pioneers and settlers on their way to the west. B. the Oregon Trail , Mormon Trail, and Pony Express wagon train routes all cover the northern edge of the Laramie Mountains .
On their west side, the Laramie Mountains are accompanied by three intermontane basins, (from north to south) the Shirley, Hanna and Laramie basins. The height of these basin landscapes is rarely below 2135 meters. The northern Shirley Basin - a wide, semi-desert plateau - gradually rises southwest from 2100 meters to the edge of the Shirley Mountains (at 2400 meters). The Laramie Basin separates the Laramie Mountains from the Medicine Bow Mountains to the south and west; apart from occasional depressions such as B. Cooper Lake at 2130 meters above sea level, or depressions blown by the wind - only rarely lower than 2135 meters.
geology
The Laramian orogeny was named after the Laramie Mountains . This was decisive for the uplift of the North American Plate in the period 72 - 40 million years ago and thus a major stage in the formation process of today's Rocky Mountains.
Like the other mountain ranges of the central Rocky Mountains, the Laramie Mountains are also a basement block raised by steep faults , which is laterally framed by Paleozoic and Mesozoic sedimentary overburden . The basement consists of the Wyoming Craton north of the Laramie River - archaic gneisses and migmatites intruded by granites (on Laramie Peak) and granodiorites and in places overlaid by a supracrustal , metamorphic volcanic-sedimentary sequence (on Elmers Rock ). To the south follows the north- verging thrust of the approximately 1750 million year old and northeast-trending Cheyenne Belt , which belongs to the Paleoproterozoic Colorado Orogen and is in turn interspersed with numerous magmatic intrusions (granites, anorthosites , syenites and monzonites ) from the Mesoproterozoic Era . The Sherman Granite is representative of this . The granite is weathered like an island mountain and rises in several knolls over a broad erosion area (stepped treeless plateau), which is about 2135 meters high. The granitic soils are no more than 30 centimeters thick here.
ecology
In the Laramie Mountains there are essentially three ecological altitude levels (in the sense of Carpenter):
- Canadian level
- Transition stage
- Upper Sonoran level
The Hudsonian stage is said to still be present on Laramie Peak, but fauna and flora are practically non-existent on this granite peak and thus prohibit judgment. For height zoning see also Porter and Cary. The transition from the prairie to the mountain level takes place very gradually on the eastern and northeastern slopes of the southern Laramie Mountains (between Cheyenne and Laramie), but in the northern part it is much more abrupt and partly interrupted - the heights vary between 1370 meters on the north Platte River and 3,131 feet at Laramie Peak. On the western slopes, the difference in altitude is much smaller (between 2135 and 3131 meters).
On its way through the Laramie Mountains , the Laramie River dug a gorge through the mountains west of Wheatland , and further east at Fort Laramie it flows into the North Platte River. This canyon represents an important ecological boundary that divides the mountain range in two. This is where the closed coniferous forests of the northern part end. The southern part is a much drier, more open landscape that has almost no forests - an exception is Pole Mountain (and the surrounding area) with its granite rocks near Vedauwoo, which are so popular with climbers and picnic friends .
The Interstate 25 freeway between Casper and Cheyenne offers beautiful views of the mountain range.
See also
credentials
- ^ Carpenter, JR 1956. An Ecological Glossary. Hafner, NY.
- ↑ Porter, CL 1962. A flora of Wyoming. Part I. Bulletin of the University of Wyoming Agricultural Experimental Station. 402
- ^ Cary, M., 1917. Life zone investigations in Wyoming. Bulletin USDA Biological Survey. 42: 1-95.
swell
- Blackstone, DL 1971. Traveler's guide to the geology of Wyoming. Bulletin of the Geological Survey of Wyoming. 55: 1-90.
- Dunbar, CO 1960. Historical Geology. J. Wiley & Sons, NY. 2nd Ed., Fig. 308
- Frost, CD, Frost, BR, Chamberlain, KR & Edwards, BR (1999). Petrogenesis of the 1.43 Ga Sherman Batholith, SE Wyoming, USA: a Reduced, Rapakivi-type Anorogenic Granite
- Hardesty, Richard L. and Groothuis, Dennis R. Butterflies of the Laramie Mountains, Wyoming (Lepidoptera: Rhopalocera.) The introduction provides additional information on the Laramie Mountains. A PDF version of this work can be found at Butterflies of the Laramie Mountains, Wyoming (Lepidoptera: Rhopalocera.) .
- Marshall, K. & Colbert, EH 1965. Stratigraphy and Life History. J. Wiley & Sons, NY.
- Sims, PK, Finn, CA & Rystrom, VL (2001). Preliminary Basement Map showing geologic-geophysical domains, Wyoming. USGS Open-File Report 01-199