The Mojave desert is located in San Bernardino County of California. The desert is a natural region that occupies a large portion of Southern California. The area is bordered by the Tehachapi Mountains to the northwest, and to the southwest by several different mountain ranges (Map 1A) and they are; the Sierra Pelona, the San Gabriel, and the San Bernardino. The Providence Mountains are visible throughout most of the eastern Mojave, with peaks reaching 7,000 feet and barrel cacti along its slopes. There are many low mountain ranges present in the Mojave that separate undrained alluviated basins. One of the East Mojaves chief attractions is the rolling hills, which encompasses an ancient Joshua Tree forest that contains an estimated 325,000 trees, with at least 25,000 of them 500 years old (Watkins p41). The second chief attraction, just to the south of the Joshua Tree forest, is a huge volcanic blister of land called the Cima Dome (Map 1B). The Mojave is the longest river in California, and has one of the largest drainage areas. But today the Mojaves channel is usually dry, due to high evaporation rate and diversion of water for agricultural purposes. The average elevation of the Mojave is 2500ft.
The low elevations of the Mojave Desert are hot and dry, reaching daily mean maximum temperatures of 100 F from June to September. Winter days in the Mojave can be warm during midday, but the night temperatures are much cooler, bringing hard frost, especially in the higher elevations. During the summer months the temperature often falls from above 100F during midday to below 74F during the night. During the winter months, the temperature is usually below 32F, and it rises to about 70F during the day. Therefore there are broad ranges of high and low temperatures, (On November 20,1994 the temp. range was 28F to 60F, at Zzyzx) and relatively high year round temperatures.
There are also occasionally strong seasonal winds, low humidity, and nominal annual precipitation. Like most deserts, the Mojave has highly variable rainfall, between 2.23 to 6.5 inches (56-165mm) per year (Norris p127). Since precipitation and humidity are slight, and temperatures generally high, the climate is usually classified as arid. Due to the fact that the Mojave Desert an arid climate results. The Mojave Desert receives less than six inches of rain annually, receiving the largest portion of rain during the winter months between October and March. The rainfall during this time is very important, because its the primary source of water contributing to the water table, the springs(such as two at Zzyzx), vegetation, and also the geomorphic processes of the desert. When fluctuations occur in the rainfall, there are noticeable effects.
During spring, the Mojave Desert is full of fields covered with Kennedys mariposa (Calochortus kennedyi), a lily with large orange-chrome petals and contrasting purple anthers. Also during the spring, the Mojave aster (Aster abatus), with lilac-colored flowers on tall, graceful stems, blooms in abundance. The desert is rich in the number of its woody herbs and shrubs, which are generally gray-green in color. The farther northeast into the deserts interior, the more stunted the shrubs become. The number of species also decreases, until one reaches the eastern Mojave Desert, where creosote bush (Larrea tridentata) and the burrow-wed dwell in areas such as Afton Canyon. In the higher elevations of the Mojave, spiny hop sage (Grayia spinosa) can be found, which have winged fruits that are pink and burgundy. Several shrubby herbaceous perennials are obvious in the sand washes of the Mojave. Among them are the fine-stemmed match weeds (Gutierrezia), which are valuable as tinder for fires, the gritty leafed sand-paper bush (Petalonyx thurberi), and several of the resin-filled ericamerias. Of shrubby yuccas, the Mojave yucca (Yucca mohavensis) is the most notable. The stems contain long, yellow-green, dagger-like leaves, that can grow over six feet high. The spiny-fruited cholla (O. parishii) is a cactus that sometimes resembles dearhorn cactus and is found in the higher mountains of the eastern Mojave. Grizzly bear cactus (O. ursina) is a popular cactus that has long ashy-gray white spine (3-10 inches long). Sage brush communities can be found in the Great Basin and in the higher elevations too. Also in the higher elevations of the east Mojave, Joshua Tree communities are found with pinyon or sagebrush. On Ventifact Hill, Barrel cactus (Fig. 1) and Prickley Pear (Fig. 2) cactus were observed. The tree yucca (Yucca brevifolia) is one of the most spectacular and most characteristic tree of the Mojave Desert.
Une fissure et l'édifice s'écroule, inaugurant la lecture infinie de ses ruines
