California's Colorado Desert is a part of the larger Sonoran Desert. It encompasses 7 million acres, including the irrigated Coachella and Imperial valleys, it is home to fauna. The Colorado Desert is a subdivision of the larger Sonoran Desert encompassing 7 million acres; the desert encompasses Imperial County and includes parts of San Diego County, Riverside County, a small part of San Bernardino County. Most of the Colorado Desert lies at a low elevation, below 1,000 feet, with the lowest point of the desert floor at 275 feet below sea level, at the Salton Sea. Although the highest peaks of the Peninsular Ranges reach elevations of nearly 10,000 feet, most of the region's mountains do not exceed 3,000 feet. In this region, the geology is dominated by the transition of the tectonic plate boundary from rift to fault; the southernmost strands of the San Andreas Fault connect to the northernmost extensions of the East Pacific Rise. The region is subject to earthquakes, the crust is being stretched, which will result in a sinking of the terrain over time.
The Colorado Desert's climate distinguishes it from other deserts. The region experiences greater summer daytime temperatures than higher-elevation deserts and never experiences frost. In addition, the Colorado Desert experiences two rainy seasons per year toward the southern portion of the region; the west coast Peninsular Ranges, or other west ranges, of Southern California–northern Baja California, block most eastern Pacific coastal air and rains, producing an arid climate. Other short or longer-term weather events can move in from the Gulf of California to the south, are active in the summer monsoons; these include remnants of Pacific hurricanes, storms from the southern tropical jetstream, the northern intertropical convergence zone. The region's terrestrial habitats include creosote bush scrub. Higher elevations are dominated by pinyon pine and California juniper, with areas of manzanita and Coulter pine. In addition to hardy perennials, more than half of the desert's plant species are herbaceous annuals, appropriately timed winter rains produce abundant early spring wildflowers.
In the southern portion of the region, the additional moisture supplied by summer rainfall fosters the germination of summer annual plants and supports smoketree and palo verde trees. Common desert wildlife include mule deer, desert kangaroo rat, cactus mouse, black-tailed jackrabbit, Gambel's quail, red-diamond rattlesnake. Among sensitive species are flat-tailed horned lizard, Coachella Valley fringe-toed lizard, desert tortoise, prairie falcon, Andrews' dune scarab beetle, peninsular bighorn sheep, California leaf-nosed bat; the best place to spot wildlife is at the wetland refuges along the Colorado River, Cibola National Wildlife Refuge and Imperial National Wildlife Refuge. In the Colorado Desert's arid environment and wetland habitats are limited in extent but are critically important to wildlife. Runoff from seasonal rains and groundwater springs forms desert arroyos, desert fan palm oases, freshwater marshes, brine lakes, desert washes and perennial streams, desert riparian vegetation communities dominated by cottonwood and non-native tamarisk.
Two of the region's most significant aquatic systems are the Colorado River. While most desert wildlife depend on aquatic habitats as water sources, a number of species, such as the arroyo toad, desert pupfish, Yuma rail, southwestern willow flycatcher, are restricted to these habitats. In some places, summer rains produce short-lived seasonal pools that host uncommon species like Couch's spadefoot toad. Desert fan palm oases are rare, they occur only where permanent water sources are available, such as at springs or along fault lines, where groundwater is forced to the surface by the movement of hard impermeable rock, can be found in the San Jacinto, Santa Rosa, Little San Bernardino mountains, in the canyons of Anza-Borrego Desert State Park, along the San Andreas Fault in the Coachella Valley. The only palm native to California, Washingtonia filifera, grows at the oases; some sub-regions of the Colorado Desert contain endemic flora. Along the Lower Colorado River Valley, in-flow side canyons, flatlands, or low-to-higher level elevations, at least three such flora occur: Hesperocallis undulata, Nolina bigelovii, Peucephyllum schottii.
Joshua Tree National Park Imperial NWR Sonny Bono Salton Sea NWR Indio Hills Palms Anza-Borrego Desert State Park Ocotillo Wells State Vehicular Recreation Area Picacho State Recreation Area Heber Dunes State Vehicular Recreation Area Salton Sea State Recreation Area The Colorado Desert is one of the least-populous regions in California, but human activities have had substantial impacts on the region's habitats and wildlife. Many unique communities aquatic and dune systems, are limited in distribution and separated by vast expanses of inhospitable, arid desert terrain. Limited human disturbances can have markedly deleterious effects on the endemic and sensitive species supported by these unique regional systems; some of the greatest human-caused effects on the region have resulted from the water diversions and flood control measures along the Colorado River. These measures have altered the region's hydrology by redistributing the region's water supp
The Mojave Desert is an arid rain-shadow desert and the driest desert in North America. It is in the southwestern United States within southeastern California and southern Nevada, it occupies 47,877 sq mi. Small areas extend into Utah and Arizona, its boundaries are noted by the presence of Joshua trees, which are native only to the Mojave Desert and are considered an indicator species, it is believed to support an additional 1,750 to 2,000 species of plants. The central part of the desert is sparsely populated, while its peripheries support large communities such as Las Vegas, Lancaster, Victorville, St. George; the Mojave Desert is bordered by the Great Basin Desert to its north and the Sonoran Desert to its south and east. Topographical boundaries include the Tehachapi Mountains to the west, the San Gabriel Mountains and San Bernardino Mountains to the south; the mountain boundaries are distinct because they are outlined by the two largest faults in California – the San Andreas and Garlock faults.
The Mojave Desert displays typical range topography. Higher elevations above 2,000 ft in the Mojave are referred to as the High Desert; the Mojave Desert occupies less than 50,000 sq mi, making it the smallest of the North American deserts. The Mojave Desert is referred to as the "high desert", in contrast to the "low desert", the Sonoran Desert to the south; the Mojave Desert, however, is lower than the Great Basin Desert to the north. The spelling Mojave originates from the Spanish language while the spelling Mohave comes from modern English. Both are used today, although the Mojave Tribal Nation uses the spelling Mojave; the Mojave Desert receives less than 2 inches of rain a year and is between 2,000 and 5,000 feet in elevation. The Mojave Desert contains the Mojave National Preserve, as well as the lowest and hottest place in North America: Death Valley at 282 ft below sea level, where the temperature surpasses 120 °F from late June to early August. Zion National Park in Utah lies at the junction of the Mojave, the Great Basin Desert, the Colorado Plateau.
Despite its aridity, the Mojave has long been a center of alfalfa production, fed by irrigation coming from groundwater and from the California Aqueduct. The Mojave is a desert of two distinct seasons. Winter months bring comfortable daytime temperatures, which drop to around 25 °F on valley floors, below 0 °F at the highest elevations. Storms moving from the Pacific Northwest can bring rain and in some places snow. More the rain shadow created by the Sierra Nevada as well as mountain ranges within the desert such as the Spring Mountains, bring only clouds and wind. In longer periods between storm systems, winter temperatures in valleys can approach 80 °F. Spring weather continues to be influenced by Pacific storms, but rainfall is more widespread and occurs less after April. By early June, it is rare for another Pacific storm to have a significant impact on the region's weather. Summer weather is dominated by heat. Temperatures on valley floors can soar above 130 °F at the lowest elevations. Low humidity, high temperatures, low pressure, draw in moisture from the Gulf of Mexico creating thunderstorms across the desert southwest known as the North American monsoon.
While the Mojave does not get nearly the amount of rainfall the Sonoran desert to the south receives, monsoonal moisture will create thunderstorms as far west as California's Central Valley from mid-June through early September. Autumn is pleasant, with one to two Pacific storm systems creating regional rain events. October is one of the sunniest months in the Mojave. After temperature, wind is the most significant weather phenomenon in the Mojave. Across the region windy days are common. During the June Gloom, cooler air can be pushed into the desert from Southern California. In Santa Ana wind events, hot air from the desert blows into the Los Angeles basin and other coastal areas. Wind farms in these areas generate power from these winds; the other major weather factor in the region is elevation. The highest peak within the Mojave is Charleston Peak at 11,918 feet, while the Badwater Basin in Death Valley is 279 feet below sea level. Accordingly and precipitation ranges wildly in all seasons across the region.
The Mojave Desert has not supported a fire regime because of low fuel loads and connectivity. However, in the last few decades, invasive annual plants such as some within the genera Bromus and Brassica have facilitated fire; this has altered many areas of the desert. At higher elevations, fire regimes are infrequent; the Mojave Desert is defined by numerous mountain ranges creating its xeric conditions. These ranges create valleys, endorheic basins, salt pans, seasonal saline lakes when precipitation is high enough. These
The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona, United States. The Grand Canyon is 277 miles long, up to 18 miles wide and attains a depth of over a mile; the canyon and adjacent rim are contained within Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Parashant National Monument, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, visited it on numerous occasions to hunt and enjoy the scenery. Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 to 6 million years ago.
Since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs deepening and widening the canyon. For thousands of years, the area has been continuously inhabited by Native Americans, who built settlements within the canyon and its many caves; the Pueblo people considered the Grand Canyon a holy site, made pilgrimages to it. The first European known to have viewed the Grand Canyon was García López de Cárdenas from Spain, who arrived in 1540; the Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, is one of the six distinct physiographic sections of the Colorado Plateau province. It is not the deepest canyon in the world. However, the Grand Canyon is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the thick sequence of ancient rocks that are well preserved and exposed in the walls of the canyon; these rock layers record much of the early geologic history of the North American continent.
Uplift associated with mountain formation moved these sediments thousands of feet upward and created the Colorado Plateau. The higher elevation has resulted in greater precipitation in the Colorado River drainage area, but not enough to change the Grand Canyon area from being semi-arid; the uplift of the Colorado Plateau is uneven, the Kaibab Plateau that Grand Canyon bisects is over one thousand feet higher at the North Rim than at the South Rim. All runoff from the North Rim flows toward the Grand Canyon, while much of the runoff on the plateau behind the South Rim flows away from the canyon; the result is deeper and longer tributary washes and canyons on the north side and shorter and steeper side canyons on the south side. Temperatures on the North Rim are lower than those on the South Rim because of the greater elevation. Heavy rains are common on both rims during the summer months. Access to the North Rim via the primary route leading to the canyon is limited during the winter season due to road closures.
The Grand Canyon is part of the Colorado River basin which has developed over the past 70 million years, in part based on apatite /He thermochronometry showing that Grand Canyon reached a depth near to the modern depth by 20 Ma. A recent study examining caves near Grand Canyon places their origins beginning about 17 million years ago. Previous estimates had placed the age of the canyon at 5–6 million years; the study, published in the journal Science in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. There is a substantial amount of controversy because this research suggests such a substantial departure from prior supported scientific consensus. In December 2012, a study published in the journal Science claimed new tests had suggested the Grand Canyon could be as old as 70 million years. However, this study has been criticized by those who support the "young canyon" age of around six million years as " attempt to push the interpretation of their new data to their limits without consideration of the whole range of other geologic data sets."The canyon is the result of erosion which exposes one of the most complete geologic columns on the planet.
The major geologic exposures in the Grand Canyon range in age from the 2-billion-year-old Vishnu Schist at the bottom of the Inner Gorge to the 230-million-year-old Kaibab Limestone on the Rim. There is a gap of about a billion years between the 500-million-year-old stratum and the level below it, which dates to about 1.5 billion years ago. This large unconformity indicates a long period. Many of the formations were deposited in warm shallow seas, near-shore environments, swamps as the seashore advanced and retreated over the edge of a proto-North America. Major exceptions include the Permian Coconino Sandstone, which contains abundant geological evidence of aeolian sand dune deposition. Several parts of the Supai Group were deposited in non–marine environments; the great depth of the Grand Canyon and the height of its strata can be attributed to 5–10 thousand feet of uplift of the Colorado Plateau, starting about 65 million years ago. This uplift has steepened the stream gradient of the Colorado River
Green River (Colorado River tributary)
The Green River, located in the western United States, is the chief tributary of the Colorado River. The watershed of the river, known as the Green River Basin, covers parts of Wyoming and Colorado; the Green River is 730 miles long, beginning in the Wind River Mountains of Wyoming and flowing through Wyoming and Utah for most of its course, except for 40 miles into western Colorado. Much of the route is through the Colorado Plateau and through some of the most spectacular canyons in the United States, it is only smaller than the Colorado when the two rivers merge, but carries a larger load of silt. The average yearly mean flow of the river at Green River, Utah is 6,121 cubic feet per second; the status of the Green River as a tributary of the Colorado River came about for political reasons. In earlier nomenclature, the Colorado River began at its confluence with the Green River. Above the confluence the Colorado was called the Grand River. In 1921, Colorado U. S. Representative Edward T. Taylor petitioned the Congressional Committee on Interstate and Foreign Commerce to rename the Grand River as the Colorado River.
On July 25, 1921, the name change was made official in House Joint Resolution 460 of the 66th Congress, over the objections of representatives from Wyoming and Utah and the United States Geological Survey which noted that the drainage basin of the Green River was more extensive than that of the Grand River, although the Grand carried a higher volume of water at its confluence with the Green. It rises in western Wyoming, in northern Sublette County, on the western side of the Continental Divide in the Bridger-Teton National Forest in the Wind River Range, it flows south through Sublette County and western Wyoming in an area known as the Upper Green River Valley southwest and is joined by the Big Sandy River in western Sweetwater County. At the town of La Barge, it flows into Fontenelle Reservoir, formed by Fontenelle Dam. Below there, it flows through open sage covered rolling prairie where it is crossed by the Oregon and Mormon emigration trails and further south until it flows past the town of Green River and into the Flaming Gorge Reservoir in Southwestern Wyoming, formed by the Flaming Gorge Dam in northeastern Utah.
Prior to the creation of the reservoir, the Blacks Fork joined the Green River south of Green River, today the mouth of Blacks Fork is submerged by the reservoir. South of the dam it flows eastward, looping around the eastern tip of the Uinta Mountains going from Utah into northwestern Colorado and through Browns Park before turning west and south into Dinosaur National Monument where it passes through the Canyon of the Lodore and is joined by the Yampa River at Steamboat Rock, it turns westward back into Utah along the southern edge of the Uintas in Whirlpool Canyon. In Utah it meanders southwest across the Yampa Plateau and through the Uintah and Ouray Indian Reservation and the Ouray National Wildlife Refuge. Two miles south of Ouray, Utah, it is joined by Duchesne River, three miles downstream by the White River. Ten miles farther downstream it is joined by the Willow River. South of the plateau, it is joined by Nine Mile Creek enters the Roan Cliffs where it flows south through the back-to-back Desolation and Gray canyons, with a combined length of 120 mi.
In Gray Canyon, it is joined by the Price River. South of the canyon it passes the town of Green River, Utah and is joined by the San Rafael River in southern Emery County. In eastern Wayne County it meanders through Canyonlands National Park; the Flaming Gorge Dam in Utah is a significant regional source of water for irrigation and mining, as well as for hydroelectric power. Begun in the 1950s and finished in 1963, it was controversial and opposed by conservationists. A dam was to be built in Whirlpool Canyon, but the conservationist movement traded the Flaming Gorge dam for halting that proposal. Apocryphally, the Sierra Club, a not-for-profit environmental organization, lost its tax-exempt status for political action in opposing the proposed dam; the Green is a large, powerful river. It ranges from 100 to 300 feet wide in the upper course to 300 to 1,500 feet wide in its lower course and ranges from 3 to 50 feet in depth, it is navigable by small craft throughout its course and by large motorboats upstream to Flaming Gorge Dam.
Near the areas where the Oregon Trail crosses, the river is 400 - 500 feet wide and averages about 20 feet deep at normal flow. Archaeological evidence indicates that the tributary canyons and sheltered areas in the river valley were home to the Fremont Culture, which flourished from the 7th century to the 13th century; the Fremont were a semi-nomadic people who lived in pithouses and are best known for the rock art on canyon walls and in sheltered overhangs. In centuries, the river basin was home to the Shoshone and Ute peoples, both nomadic hunters; the Shoshone inhabited the river valley north of the Uinta Mountains, whereas the Utes lived to the south. The current reservation of the Utes is in the Uintah Basin; the Shoshone called the river the Seeds-kee-dee-Agie, meaning "Prairie Hen River." In 1776, the Spanish friars Silvestre Vélez de Escalante and Francisco Atanasio Domínguez crossed the river near present-day Jensen, naming it the Rio de San Buenaventura. The map-maker of the expedition, Captain Bernardo Miera y Pacheco, erroneously indicated that the river flowed southwest to what is now known as Sevier Lake.
Cartographers extended the error, representing the Buenaventura River as flowing into the Pacific Ocean. At least one charted the Buenaventura as draining the Great Salt Lake. Spanish
The Sonoran Desert is a North American desert which covers large parts of the Southwestern United States in Arizona and California and of Northwestern Mexico in Sonora, Baja California, Baja California Sur. It is the hottest desert in Mexico, it has an area of 260,000 square kilometers. The western portion of the United States–Mexico border passes through the Sonoran Desert. In phytogeography, the Sonoran Desert is within the Sonoran Floristic Province of the Madrean Region in southwestern North America, part of the Holarctic Kingdom of the northern Western Hemisphere; the desert contains a variety of unique and endemic plants and animals, such as the saguaro and organ pipe cactus. The Sonoran desert wraps around the northern end of the Gulf of California, from Baja California Sur, north through much of Baja California, excluding the central northwest mountains and Pacific west coast, through southeastern California and southwestern and southern Arizona to western and central parts of Sonora.
It is bounded on the west by the Peninsular Ranges, which separate it from the California chaparral and woodlands and Baja California Desert ecoregions of the Pacific slope. To the north in California and northwest Arizona, the Sonoran Desert transitions to the colder-winter, higher-elevation Mojave, Great Basin, Colorado Plateau deserts. To the east and southeast, the deserts transition to the coniferous Arizona Mountains forests and Sierra Madre and Sierra Madre Occidental pine–oak forests at higher elevations. To the south the Sonoran–Sinaloan transition subtropical dry forest is the transition zone from the Sonoran Desert to the tropical dry forests of the Mexican state of Sinaloa; the desert's sub-regions include the Colorado Desert of southeastern California. In the 1957 publication Vegetation of the Sonoran Desert, Forrest Shreve divided the Sonoran Desert into seven regions according to characteristic vegetation: Lower Colorado Valley, Arizona Upland, Plains of Sonora, Foothills of Sonora, Central Gulf Coast, Vizcaíno Region, Magdalena Region.
Many ecologists now consider Shreve's Vizcaíno and Magdalena regions, which lie on the western side of the Baja California Peninsula, to be a separate ecoregion, the Baja California Desert. Within the southern Sonoran Desert in Mexico is found the Gran Desierto de Altar, with the Reserva de la Biosfera el Pinacate y Gran Desierto de Altar, extending 2,000 square kilometers of desert and mountainous regions; the Pinacate National Park includes the only active erg dune region in North America. The nearest city to the Reserva de la Biosfera el Pinacate y Gran Desierto de Altar is Puerto Peñasco in the state of Sonora, Mexico. Sub-regionsSonoran Desert sub-regions include: Colorado Desert Gran Desierto de Altar Lechuguilla Desert Tonopah Desert Yuha Desert Yuma Desert The Sonoran Desert includes 60 mammal species, 350 bird species, 20 amphibian species, over 100 reptile species, 30 native fish species, over 1000 native bee species, more than 2,000 native plant species; the Sonoran Desert area southeast of Tucson and near the Mexican border is vital habitat for the only population of jaguars living within the United States.
The Colorado River Delta was once an ecological hotspot within the Sonoran desert, fueled by the flow of fresh water through the Colorado river in this otherwise dry area, but the delta has been reduced in extent due to the damming and use of the river upstream. Many plants not only thrive in the harsh conditions of the Sonoran Desert. Many have evolved to have specialized adaptations to the desert climate; the Sonoran Desert's biseasonal rainfall pattern results in more plant species than any other desert in the world. The Sonoran Desert includes plant genera and species from the agave family, palm family, cactus family, legume family, numerous others; the Sonoran is the only place in the world. Cholla, hedgehog, prickly pear, nightblooming cereus, organ pipe are other taxa of cacti found here. Cactus provides food and homes to many desert mammals and birds, with showy flowers in reds, pinks and whites, blooming most from late March through June, depending on the species and seasonal temperatures.
Creosote bush and bur sage dominate valley floors. Indigo bush and Mormon tea are other shrubs. Wildflowers of the Sonoran Desert include desert sand verbena, desert sunflower, evening primroses. Ascending from the valley up bajadas, various subtrees such as velvet mesquite, palo verde, desert ironwood, desert willow, crucifixion thorn are common, as well as multi-stemmed ocotillo. Shrubs found at higher elevations include whitethorn acacia, fairy duster, jojoba. In the desert subdivisions found on Baja California, cardon cactus, elephant tree, boojum tree occur; the California fan palm is found in the Colorado Desert section of the Sonoran Desert, the only native palm in California, among many other introduced Arecac