MOJAVE BASIN & RANGE: Hoover Dam – Mesquite
Location: The Mojave Basin and Range is located in southeastern California, southern Nevada, southwestern Utah, and northwestern Arizona.
Climate: The ecoregion has a dry, subtropical desert climate, marked by hot summers and warm winters. The mean annual temperature is approximately 5°C at high elevations, and 24°C in the lowest basins. Death Valley, in the central part of the region, is one of the hottest places on the continent, with summer temperatures sometimes reaching over 56°C. The frost-free period ranges from 150 days in colder areas to 350 days in the warmer valleys. Mean annual precipitation is 167 mm, and ranges from 50 to over 900 mm on the wetter high peaks. Snow occurs in the mountains, but is uncommon at lower elevations.
Vegetation: The desert vegetation is sparse, predominantly creosote bush, compared to the mostly saltbush-greasewood and Great Basin sagebrush of ecoregion 10.1.5 to the north, or creosote bush, sage and palo verde-cactus shrub and saguaro cactus in the Sonoran Desert (10.2.2) to the south. In the Mojave, creosote bush, white bursage, Joshua-tree and other yuccas, and blackbrush are typical. On alkali flats, saltbush, saltgrass, alkali sacaton, and iodinebush are found. In the mountains, sagebrush, juniper, singleleaf pinyon, ponderosa pine, white fir, limber pine, and some bristlecone pine (the world’s longest- living trees) occur.
Hydrology: Surface water is scarce; if present, streams are mostly intermittent and ephemeral. The Colorado River crosses the eastern portion of the region. Some springs, seeps, and ponds occur.
A visit to Hoover Dam reveals the grandeur of engineering that went into the design and construction of this hydro-electric facility. Its impact on the the ecoregion was enormous as Mojave Basin and Range lands were consumed by water. The following set of photos is placed here to show the effect the dam has on the flow of the Colorado River…
The Virgin River empties into the Colorado River at the Lake Mead Resevoir near Mesquite.
Terrain: This ecoregion contains scattered north-south trending mountains that are generally lower than those of the Central Basin and Range (10.1.5). Broad basins, valleys, and old lakebeds occur between the ranges, with long alluvial fans. Elevations range from 85 m below sea level in Death Valley, to more than 3,300 masl on the highest mountain peaks. Deep Quaternary alluvial deposits are present on valley floors and alluvial fans. Geology is complex, with intrusive granitics and other igneous rocks, recent volcanics, metamorphic, and sedimentary rocks, including some carbonates. Typical soils are Aridisols and Entisols with a thermic and hyperthermic soil temperature regime and aridic soil moisture regime.
Terrain side-trip: Interstate 15 take a short swerve back into Arizona just before crossing the Utah border. This section of road passages through a breath-taking visual surprise through the Virgin River Canyon.
Wildlife: Representative wildlife include desert bighorn sheep, pronghorn, coyote, kit fox, black-tail jackrabbit, desert cottontail rabbit, greater roadrunner, Gambel’s quail, mourning dove, desert tortoise, and rattlesnake.
Land Use/Human Activities: Most of this region is federally owned and there is relatively little grazing activity because of the lack of water and forage for livestock. Public and federal land is in the form of national parks and numerous military reservations. Another economic activity is mining of silver, gold, talc, boron, and borate minerals. Recreation and tourism are also important. Heavy use of off-road vehicles and motorcycles in some areas has caused severe wind and water erosion problems. Large cities include Las Vegas.
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Commission for Environmental Cooperation; North American Terrestrial Ecoregions—Level III; April 2011.
Photos taken in October 2013 along highways-
Route 93, I-15
Just Another Nature Enthusiast Photography by Jane Wilson is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.