Whipple Mountains

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The Whipple Mountains ( Avii Kur'utat in the Mohave Indian language) are located in southeastern California , south of Lake Havasu City and north of the city of Parker , both in the state of Arizona . The ridge of the Whipple Mountains extends for around 40 kilometers in an east-west direction. It belongs to San Bernardino County and forms part of the Colorado Desert , the northwestern end of the Sonoran Desert . There are many mines in the Whipple Mountains, including the Independence Mine and the Bessie Mine.

etymology

The Whipple Mountains were named in honor of Amiel Weeks Whipple , a US topographer and brigadier general.

cartography

The following "7.5 'Quadrangle maps" (geological maps over an area of ​​7.5 arc minutes) of the United States Geological Survey (USGS) cover the area of ​​the Whipple Mountains:

  • Gene Wash
  • Havasu Lake
  • Lake Havasu City South
  • Parker
  • Parker NW
  • Savahia Peak
  • Whipple Mountains SW
  • Whipple Wash

climate

The records of the Western Regional Climate Center show the extreme aridity (less than 150 millimeters of precipitation per year) of the Whipple Mountains. The temperatures in summer are very high (+ 40 ° C) and winters are mild.

geography

The Whipple Mountains are surrounded by the Colorado River in the northeast and southeast . The Mopah Range follows further to the west, and the Chemehuevi Mountains to the north .

The highest point of the Whipple Mountains is an unnamed peak on the immediate western edge with a height of 1311 meters. In the wilderness reserve, Whipple Peak reaches 1,259 meters. The highest climbing peak is Savahia Peak , located in the western part, at 821 meters. If one takes into account that the Colorado River at Poston is only 95 meters as a base level, the Whipple Mountains reach a height difference of at least 1000 meters.

Today's landscape of the Whipple Mountains consists of a series of more or less parallel ridges that extend in a north-west-south-east direction. The Whipple Wash (a large dry valley ) runs perpendicular to it, dividing the entire eastern part into two halves and draining it northeast to the Colorado River when it rains.

geology

The Whipple Mountains are known among geologists as one of the world's most open-minded and most studied metamorphic core complexes .

The straight ridges already mentioned above are the edges of tilted crust blocks in the hanging wall of a large-scale shear . On the west side, the rocks of the hanging wall were completely removed, so that now anticline arched, light green mylonites of the lower crust come to light . In the eastern section there are unchanged, rust-red tertiary volcanic rocks and sedimentary rocks ( fanglomerates ) in the hanging wall of the shear horizon , which were discordantly deposited over non-mylonitic crystalline of the Precambrian and now generally dip to the west. The crystalline belongs to the geological terran Mojavia (also Mojave Province ). It was interspersed with intrusive rocks in the Upper Cretaceous around 90 million years ago ( tonalite , quartz diorite ).

The shear horizon with the overlying rocks of the hanging wall can be reached by means of larger dry valleys. Along the shear horizon, which has chloritic breccias that can become up to 300 meters thick , there are prime examples of hydrothermal rock transformations and the injection of cataclasites in the flowing state. In addition, there is the opportunity to study the behavior of faults in the middle and upper crustal area directly using many examples. Furthermore, a number of steep faults in the hanging wall are clearly exposed; they illustrate in an impressive way the tilting movements of the upper crustal area caused by stretching.

During the Early and Middle Miocene, the central and southern Basin and Range Province , which includes the Whipple Mountains, was subject to severe crustal expansion between the more rigid crustal blocks of the Sierra Nevada and the Colorado Plateau . In a crust section that is now 70 to 100 kilometers wide, more than 40 kilometers (i.e. 70-130%) of expansion was recorded.

The shearing movements had started in the Whipple Mountains with the beginning of the Miocene BP 21.5 million years ago and lasted until 14 million years BP (Middle Miocene, Serravallian ). The direction of movement of the hanging wall was directed towards the northeast and an offset of more than 60 kilometers was achieved. Around the same period, the rocks were additionally a potassium - metasomatism suspended.

The shear horizon in the Whipple Mountains is part of the so-called Whipple Domain - a system of flat faults inclined to the east. This area can be traced from the Whipple Mountains in a northerly direction to the southern tip of Nevada . Here there is a transition to faults inclined to the west with also flat directions of incidence.

Geobotany

The following plant communities are native to the Whipple Mountains :

It thrive and a. the following plants in this arid desert climate:

Wildlife

The mammal fauna consists of bighorn sheep , mule deer , wild ass , coyote , donkey hare , ground squirrel and kangaroo rat . Worth mentioning among the reptiles are the California gopher tortoise , whose population is endangered, as well as several species of rattlesnakes and lizards . Among the birds are quail , cuckoo-cuckoo , various owls , prairie falcon , golden eagle , round-tailed cattle and red-tailed buzzard .

history

Wyatt Earp spent his last winters in the Whipple Mountains as a gold and copper prospector from around 1906 . The settlement of Earp was named after him and is partly on or near his prospect. However, his house is in the city of Vidal .

Access and legal status

Border of the Whipple Mountains Wilderness.
The northeast end of the Whipple Wash, Whipple Mountains, California. This picture was taken in January 2005 - a time of high precipitation, which is quite atypical for this area.

The main part of the Whipple Mountains is part of the Whipple Mountains Wilderness , which is administered by a branch of the US Bureau of Land Management (BLM) in Needles . The wilderness reserve covers approximately 323.4 square kilometers, non-motorized and motorized vehicles have no access to the reserve. The interior of the Whipple Mountains can be reached on foot or on horseback, the main access route being the Whipple Wash . Motorized access to the reserve border is only possible from the northeast; in this case, the route follows the maintenance lane of an overhead line and can only be driven by four-wheel drive vehicles with a large axle height. Permission is not required for individual access, however commercial or organized groups must obtain permission from the BLM.

Individual sections inside and outside the reserve are owned by the State of California or private owners. Access to these areas is regulated by the owners and is not subject to the BLM.

Web links

Individual evidence

  1. ↑ Munro, P et al. A Mojave Dictionary Los Angeles: UCLA, 1992

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