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66-678: The eastern portion of the area contains the volcanic Pinacate Peaks region; together with the western portion, the area forms the El Pinacate y Gran Desierto de Altar Biosphere Reserve and a UNESCO World Heritage Site . The Gran Desierto covers approximately 5,700 square kilometres (2,200 sq mi), most of it in the Mexican state of Sonora. The northernmost edges reach across the international border into Organ Pipe Cactus National Monument and Cabeza Prieta National Wildlife Refuge in southwestern Arizona , United States . The region

132-625: A group of volcanic peaks and cinder cones located mostly in the Mexican state of Sonora along the international border adjacent to the U.S. state of Arizona , surrounded by the vast sand dune field of the Gran Desierto de Altar , at the desert's southeast. The Spanish name for the Pinacate Peaks geographic feature is the Sierra Pinacate, which is used in their homeland of Mexico. The Pinacate Peaks lie just north of

198-475: A diversity of flora and fauna. The 54,000 sq mi (140,000 km ) desert supports a number of human activities, including recreation, ranching, and military training. The Mojave Desert also contains various silver , tungsten , iron and gold deposits. The spelling Mojave originates from the Spanish language, while the spelling Mohave comes from modern English. Both are used today, although

264-595: A fuel bed. This has significantly altered many areas of the desert. At higher elevations, fire regimes are regular but infrequent. While the Mojave Desert is generally sparsely populated, it has increasingly become urbanized in recent years. The metropolitan areas include Las Vegas , the largest urban area in the Mojave and the largest urban area in Nevada with a population of about 2.3 million. St. George, Utah ,

330-512: A larger North American Desert . Of these, the Mojave is the smallest and driest. It displays typical basin and range topography , generally having a pattern of a series of parallel mountain ranges and valleys. It is also the site of Death Valley , which is the lowest elevation in North America. The Mojave Desert is often colloquially called the "high desert", as most of it lies between 2,000 and 4,000 feet (610 and 1,220 m). It supports

396-827: A minimum, it may be assumed that onshore coastal winds from the south were less important to sand movement when the Wisconsin shoreline was located 45 km (28 mi) seaward of its current position. The geological history of the Gran Desierto is intimately linked to the opening of the Gulf of California and the capture of the ancestral Colorado River; source areas that were adjacent to the Gran Desierto have shifted in position, basement topography has been altered continuously, and bedforms have been created, modified, or completely destroyed and then reworked. The Gran Desierto sand sheets and dunes are located atop deltaic deposits of

462-406: A natural border to the Mojave Desert. There are also abundant alluvial fans , which are called bajadas , that form around the mountains within the Mojave Desert and extend down toward the low altitude basins, which contain dried lake beds called playas, where water generally collects and evaporates, leaving large volumes of salt. These playas include Rogers Dry Lake and China Lake . Dry lakes are

528-709: A noted feature of the Mojave landscape. The Mojave Desert is also home to the Devils Playground , about 40 miles (64 km) of dunes and salt flats going in a northwest-southeasterly direction. The Devil's Playground is a part of the Mojave National Preserve and is between the town of Baker, California and the Providence Mountains . The Cronese Mountains are within the Devil's Playground. There are very few surface rivers in

594-504: A tropical faunal assemblage which supports a contention that the Colorado River delta of a previous interglacial period (>120,000 years ago) was much warmer and wetter than in the present interglacial. Paleo-deltaic deposits near Salina Grande correlate with a ubiquitous indurated shell deposit dated by Io/U radiometric methods at 146,000 +13,000/-11,000 years of age. Slate (1985) obtained K-Ar ages for basalt flows in

660-426: Is 15% in the star dunes and about 10% in the low transverse or crescentic dunes areas. These percentages are substantially greater than in most active dune fields, where vegetation covers of 15% are more typical. Several teams have examined the middens built by pack rats as a proxy for ancient vegetation regimes. All have concluded that the Gran Desierto has been an ecological refuge for desert plants since at least

726-588: Is a former ranch along the Mojave River. Several attractions and natural features are in the Calico Mountains . Calico Ghost Town , in Yermo, is administered by San Bernardino County. The ghost town has several shops and attractions and inspired Walter Knott to build Knott's Berry Farm . The Bureau of Land Management also administers Rainbow Basin and Owl Canyon. The Calico Early Man Site , in

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792-661: Is dominated by sand sheets and dunes ranging in thickness from less than 1 kilometre (0.62 mi) to greater than 12 kilometres (7.5 mi). The total volume of sand in the Gran Desierto is about 60 cubic kilometres (14 cu mi). Most of that volume was delivered by the Colorado River during the Pleistocene , which flowed through the present-day Gran Desierto area approximately 120,000 years before present. This Pleistocene delta migrated westward concomitant with strike-slip faulting and rifting associated with

858-473: Is generally abundant in winter annuals. The plants of the Mojave Desert each generally correspond to an individual geographic feature. As such, there are distinctive flora communities within the desert. Notable species of the Mojave Desert include bighorn sheep ( Ovis canadensis ), mountain lions ( Puma concolor ), black-tailed jackrabbits ( Lepus californicus ), and desert tortoises ( Gopherus agassizii ). Various other species are particularly common in

924-572: Is not endemic, but almost completely limited to the Mojave Desert. There are also aquatic species that are found nowhere else, such as the Devils Hole pupfish , limited to one hot spring near Death Valley. Before the European colonization of North America, tribes of Native Americans, such as the Mohave , were hunter-gatherers living in the Mojave Desert. European explorers started exploring

990-443: Is split equally between a western population of star dunes and an eastern set of transverse or crescentic dunes . Some of the larger crescentic dunes in the northeastern sand sea exhibit reversing crests, a transitional morphological feature associated with star dunes. Vegetation assemblages of the Gran Desierto are typical of the lower Sonoran Desert with a marked difference in vegetation type and density with location. Large areas of

1056-538: Is still occurring along the Mesa Arenosa , a drag folded fault block forming the coastal boundary. The synchronous development of the Colorado River Delta and the associated Gran Desierto sand sink continues offshore into the Gulf of California. Reports on the submarine topography of the Gulf of California by van Andel describe three former river channels on the seafloor : one originating at

1122-643: Is the northeasternmost metropolitan area in the Mojave, with a population of around 180,000 in 2020, and is located at the convergence of the Mojave, Great Basin, and Colorado Plateau. The Los Angeles exurban area of Lancaster - Palmdale has more than 400,000 residents, and the Victorville area to its east has more than 300,000 residents. Smaller cities or micropolitan areas in the Mojave Desert include Helendale , Lake Havasu City , Kingman , Laughlin , Bullhead City and Pahrump . All have experienced rapid population growth since 1990. The California portion of

1188-406: Is the principal saline basin of the Mojave Desert. Natural springs are typically rare throughout the Mojave Desert, but there are two notable springs, Ash Meadows and Oasis Valley . Ash Meadows is formed from several other springs, which all draw from deep underground. Oasis Valley draws from the nearby Amargosa River. Extremes in temperatures throughout the seasons characterize the climate of

1254-546: The Great Basin High in winter, with north-to-northeasterly winds. The well-documented pluvial epochs which occurred over much of the southwestern United States during the most-recent ( Wisconsin ) ice age may not have extended as far south as the Gran Desierto. It appears that the climatic regime of the past 150,000 years at this site has been one of gradually increasing aridity with current hyper-arid conditions being firmly in place by at least 43,000 years ago. As

1320-649: The Mexican Federal Government 's SEMARNAT - the Ministry of the Environment and Natural Resources, in collaboration with the government of the State of Sonora 's IMADES agency. Facts about the reserve: Mojave Desert The Mojave Desert ( / m oʊ ˈ h ɑː v i , m ə -/ ; Mohave : Hayikwiir Mat'aar ; Spanish : Desierto de Mojave ) is a desert in

1386-664: The Mojave Tribal Nation officially uses the spelling Mojave . Mojave is a shortened form of Hamakhaave , an endonym in their native language, which means "beside the water". The Mojave Desert is a desert bordered to the west by the Sierra Nevada mountain range and the California montane chaparral and woodlands , and to the south and east by the Sonoran Desert. The boundaries to the east of

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1452-549: The Mojave National Preserve . However, the southwest and central east portions of the Mojave Desert are particularly threatened as a result of off-road vehicles, increasing recreational use, human development, and agricultural grazing . The World Wildlife Fund lists the Mojave Desert as relatively "stable/intact". Various habitats and regions of the Mojave Desert have been protected by statute. Notably, Joshua Tree National Park, Death Valley National Park, and

1518-555: The Oligocene . Large downpours during the Miocene likely significantly eroded the rock in the Mojave and accelerated deposition . The Mojave Desert is a source of various minerals and metallic materials. Due to the climate, there is an accumulation of weathered bedrock, fine sand and silt, both sand and silt sediments becoming converted into colluvium . The deposits of gold, tungsten, and silver have been mined frequently prior to

1584-577: The Paleozoic era, the area that is now the Mojave was again likely submerged under a greater sea. During the Mesozoic era, major tectonic activities such as thrust faulting and folding resulted in distinctive shaping as well as intrusion . During the Cenozoic , more tectonic deformation occurred whilst the Mojave was partly submerged. Major volcanic activity is thought to have occurred during

1650-478: The San Gabriel Mission . In recent years, human development in the Mojave Desert has become increasingly present. Human development at the major urban and suburban centers of Las Vegas and Los Angeles has had an increasingly damaging effect on the wildlife of the Mojave Desert. An added demand for landfill space as a result of the large metropolitan centers of Las Vegas and Los Angeles also has

1716-535: The Second World War . Additionally, there have been deposits of copper , tin , lead-zinc , manganese , iron , and various radioactive substances but they have not been mined for commercial use. The flora of the Mojave Desert consists of various endemic plant species, notably the Joshua Tree , which is a notable endemic and indicator species of the desert. There is more endemic flora in

1782-534: The rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States . Named for the indigenous Mohave people , it is located primarily in southeastern California and southwestern Nevada , with small portions extending into Arizona and Utah . The Mojave Desert, together with the Sonoran , Chihuahuan , and Great Basin deserts, form

1848-757: The Calico Hills east of Yermo , is believed by some archaeologists, including the late Louis Leakey , to show the earliest evidence with lithic stone tools found here of human activity in North America. The Mojave Desert has a relatively stable and intact conservation status. The Mojave Desert is one of the best protected distinct ecoregions in the United States, as a result of the California Desert Protection Act , which designated 69 wilderness areas and established Death Valley National Park , Joshua Tree National Park , and

1914-692: The Gran Desierto in only a few millennia. The Gran Desierto is located adjacent to a rapidly subsiding tectonic basin , the Salton Trough , which is a northern extension of the Gulf of California, itself an embayment created by rifting initiated during the Pliocene along the East Pacific Rise and the San Andreas Fault system. Regional subsidence has propagated to the northwest as rifting and strike-slip faulting continues into

1980-401: The Gulf of California. Strike-slip movement in the area is as high as 60 mm/year. Since 1900, one magnitude 6.3 and two magnitude 7.1 earthquakes have originated within the erg. Most seismicity within the Gran Desierto originates at depths of 5 to 6 kilometres (3.1 to 3.7 mi), corresponding to the transition between deltaic deposits and basement crystalline rocks . Local uplift

2046-724: The Joshua tree (Yucca brevifolia). Additionally, the Mojave Desert is also home to various species of cacti, such as silver cholla ( Cylindropuntia echinocarpa ), Mojave prickly pear ( O. erinacea ), beavertail cactus ( O. basilaris ), and many-headed barrel cactus ( Echinocactus polycephalus ). Less common but distinctive plants of the Mojave Desert include ironwood ( Olneya tesota ), blue Palo Verde ( Parkinsonia Florida ), chuparosa ( Justicia californica ), spiny menodora ( Menodora spinescens ), desert senna ( Cassia armata ), California dalea ( Psorothamnus arborescens ), and goldenhead ( Acamptopappus shockleyi ). The Mojave Desert

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2112-807: The Mojave Desert are less distinctive than the other boundaries because there is no presence of an indicator species, such as the Joshua tree ( Yucca brevifolia ), which is endemic to the Mojave Desert. The Mojave Desert is distinguished from the Sonoran Desert and other deserts adjacent to it by its warm temperate climate, as well as flora and fauna such as ironwood ( Olneya tesota ), blue Palo Verde ( Parkinsonia florida ), chuparosa ( Justicia californica ), spiny menodora ( Menodora spinescens ), desert senna ( Cassia armata ), California dalea ( Psorothamnus arborescens ), California fan palm (Washingtonia filifera) and goldenhead ( Acamptopappus shockleyi ). Along with these other factors, these plants differentiate

2178-585: The Mojave Desert in the San Gabriel mountains may receive more rain. Most of the precipitation in the Mojave comes from the Pacific Cyclonic storms that are generally present passing eastward in November to April. Such storms generally bring rain and snow only in the mountainous regions, as a result of the effect of the mountains, which creates a drying effect on its leeward slopes . During

2244-629: The Mojave Desert than almost anywhere in the world. Mojave Desert flora is not a vegetation type , although the plants in the area have evolved in isolation because of the physical barriers of the Sierra Nevadas and the Colorado Plateau. Predominant plants of the Mojave Desert include all-scale ( Atriplex polycarpa ), creosote bush ( Larrea tridentata ), brittlebush ( Encelia farinosa ), desert holly ( Atriplex hymenelytra ), white burrobush (Hymenoclea salsola), and most notably,

2310-725: The Mojave Desert was further protected from development by the Desert Renewable Energy Conservation Plan (DRECP), in which the Bureau of Land Management designated 4.2 million acres of public land as protected wilderness as part of the National Conservation Lands of the California Desert. The Mojave Desert has served as a backdrop for a number of films . The 2010 video game Fallout: New Vegas takes place in

2376-596: The Mojave Desert, but two major rivers generally flow underground. One is the intermittent Mojave River , which begins in the San Bernardino mountains and disappears underground in the Mojave Desert. The other is the Amargosa River , which flows partly underground through the Mojave Desert along a southward path. The Manix, Mojave, and the Little Mojave lakes are all large but shallow. Soda Lake

2442-495: The Mojave Desert, such as the LeConte's thrasher ( Toxostoma lecontei ), banded gecko ( Coleonyx variegatus ), desert iguana (Dipsosaurus dorsalis), chuckwalla ( Sauromalus obesus ), and regal horned lizard ( Phrynosoma solare ). Species of snake include the rosy boa ( Lichanura trivirgata ), Western patch-nosed snake ( Salvadora hexalepis ), and Mojave rattlesnake ( Crotalus scutulatus ). These species can also occur in

2508-399: The Mojave Desert. Freezing temperatures as well as strong winds are not uncommon in the winter, as well as precipitation such as rain and snow in the mountains. In contrast, temperatures above 100 °F (38 °C) are not uncommon during the summer months. There is an annual average precipitation of 2 to 6 inches (51 to 152 mm), although regions at high altitudes such as the portion of

2574-793: The Mojave National Preserve by the California Desert Protection Act of 1994. ( Pub.L. 103–433). Various other federal and state land agencies have protected regions within the Mojave Desert. These include Antelope Valley California Poppy Reserve , which protects the fields of California poppies, Mojave Trails National Monument , Desert Tortoise Natural Area , Arthur B. Ripley Desert Woodland State Park , Desert National Wildlife Refuge , Lake Mead National Recreation Area , Providence Mountains State Recreation Area , Red Cliffs National Conservation Area , Red Rock Canyon State Park , Saddleback Butte State Park , Snow Canyon State Park and Valley of Fire State Park . In 2013,

2640-737: The Mojave a critical training location for the United States Department of Defense. The Mojave Desert has long been a valuable resource for people, and as its human population grows, its importance will only grow. Miners, ranchers, and farmers rely on the desert for a living. The Mojave is also used by the state of California to meet renewable energy objectives. Large tracts of the desert are owned by federal agencies and are leased at low cost by wind and solar energy companies, although these renewable developments can cause their own environmental impact and disturb cultural landscapes and visual resources. Desert Sunlight Solar Farm , one of

2706-533: The Mojave from the nearby Sonoran Desert. The Mojave Desert is bordered by the San Andreas Fault to the southwest and the Garlock fault to the north. The mountains elevated along the length of the San Andreas fault provide a clear border between the Mojave Desert and the coastal regions to the west. The Garlock fault separates the Mojave Desert from the Sierra Nevada and Tehachapi mountains, which provide

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2772-652: The Pleistocene Colorado River. The lower Colorado River was captured by the Gulf of California 1.2 million years before present. This event places an upper bound on the age of the Gran Desierto with the Colorado's major clastic sediment sources. Conglomeritic sands and silts beneath the Mesa Arenosa were examined by Colletta and Ortlieb and dated at between 700,000 and 120,000 years before present. Vertebrate fossils found by Merriam within

2838-566: The Sierra del Rosario mountains, which are surrounded by the erg on all sides. The Sierra Enterrada is a smaller inselberg almost completely buried by the sand near the boundary of the Gran Desierto and the Pinacate volcanic complex . The Gran Desierto is best known for its magnificent star dunes , many in excess of 100 metres (330 ft) high. More than two-thirds of the Gran Desierto is covered by sand sheets and sand streaks. The remaining area

2904-483: The deltaic deposits include Equus , Gomphotherium , and Bison and were assigned to Irvingtonian age (0.5 to 1.8 million years before present), dates consistent with the aforementioned capture of the lower Colorado River. Evidence of a giant anteater , Myrmecophaga tridactyla , was found in the deltaic deposits in the southern Gran Desierto. Van Devender notes that the specimen was found in association with fossils of mammoths , sloths , and boa constrictors ,

2970-410: The desert also contains Edwards Air Force Base and Naval Air Weapons Station China Lake , noted for experimental aviation and weapons projects. The Mojave Desert has several ghost towns . The most significant are the silver and copper-mining town of Calico, California , and the old railroad depot of Kelso, California . Some of the other ghost towns are more modern, created when U.S. Route 66 (and

3036-467: The deserts beginning in the 18th century. Francisco Garcés , a Franciscan friar, was the first explorer of the Mojave Desert in 1776. Garcés recorded information about the original inhabitants of the deserts. Later, as American interests expanded into California, American explorers started probing the California deserts. Jedediah Smith travelled through the Mojave Desert in 1826, finally reaching

3102-547: The eastern limit of the dune field. To the north, the sands thin out against the distal margins of alluvial fans from the Tinajas Altas and Tule Mountains along the Arizona–Sonora border. The southern border of the sand sea is the northern shore of the Gulf of California. The southernmost extension of the San Andreas Fault cuts across the area and lies beneath several prominent granite inselbergs , most notably

3168-462: The fishing resort of Puerto Peñasco . The tallest of the peaks is Cerro del Pinacate (also called Volcan Santa Clara), with an elevation of 3,904 feet (1,190 m). The Mexican Spanish word pinacate is derived from the Nahuatl word for the endemic desert stink beetle , pinacatl . The volcanoes here have erupted here sporadically since about 4 million years ago, probably in association with

3234-464: The former channel and floodplain. Deltaic sediments beneath the Gran Desierto may be as much as 6,000 metres (20,000 ft) deep. Annual sediment loads prior to the damming of the Colorado River were prodigious. A single flood event deposited an estimated 100,000,000 cubic metres (3.5 × 10 cu ft) of coarse to medium sand as a sheet deposit on the modern delta just south of the international boundary. Events like this, even if rare, could fill up

3300-793: The international destination of Las Vegas. The Mojave is also known for its scenery, playing host to Death Valley National Park , Joshua Tree National Park , and the Mojave National Preserve . Lakes Mead , Mohave , and Havasu provide water sports recreation, and vast off-road areas entice off-road enthusiasts. The Mojave Desert also includes three California State Parks , the Antelope Valley California Poppy Reserve , in Lancaster , Saddleback Butte State Park , in Hi Vista and Red Rock Canyon State Park . Mojave Narrows Park , operated by San Bernardino County,

3366-470: The largest solar farms in the world, was built approximately five miles from Joshua Tree National Park . An endangered Yuma clapper rail was found dead at the site in 2014, spurring efforts from conservation groups to protect birds from the so-called lake effect, a phenomenon in which birds can mistake the reflective glare of solar panels for a body of water. The Mojave Desert is one of the most popular spots for tourism in North America, primarily because of

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3432-459: The late Pleistocene, they do indicate that, in gross form, the climate of the Gran Desierto as recorded by plant communities has been desert-like since at least the peak of the Wisconsinan glaciation . The Gran Desierto has a warm to hot arid climate . Mean annual rainfall, most of which occurs between September and December, is 73 mm (2.9 in) at Puerto Peñasco , Sonora (located at

3498-496: The late Pleistocene. The Gran Desierto has served as a refuge for most dominant Mojave Desert plant species during cooler pluvial epochs as well. Carbon-14 dating for a midden from the Tinajas Altas Mountains shows assemblages of juniper and Joshua trees coexisting with contemporary Gran Desierto flora and fauna more than 43,000 years before present. Although midden studies do not provide information beyond

3564-442: The late summer months, there is also the possibility of strong thunderstorms, which bring heavy showers or cloudbursts. These storms can result in flash flooding . The Mojave Desert has not historically 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 , Schismus and Brassica have facilitated fires by serving as

3630-509: The lesser-known U.S. Route 91 ) were abandoned in favor of the construction of Interstates . CA SR 14 , Interstate 15 , Interstate 40 , CA SR 58 , CA SR 138 , US Route 95 , and US Route 395 are the main highways that traverse the Mojave Desert. The rock that forms the Mojave Desert was likely created under shallow water in the Precambrian . Sedimentary processes left large deposits of limestones, silicates, and dolomites. During

3696-537: The neighboring Sonoran and Great Basin deserts. The animal species of the Mojave Desert have generally fewer endemics than its flora. However, endemic fauna of the Mojave Desert include Kelso Dunes jerusalem cricket ( Ammopelmatus kelsoensis), the Kelso Dunes shieldback katydid ( Eremopedes kelsoensis ), the Mohave ground squirrel ( Spermophilus Mohavensis ) and Amargosa vole ( Microtus californicus scirpensis ). The Mojave fringe-toed lizard ( Uma Scopari a)

3762-700: The opening of the Gulf of California . The most recent volcanic activity was about 11,000 years ago. The Pinacate Desert is home to the largest sand dunes in the Americas . A variety of flora and fauna occur in the Pinacate Mountains, including the sculptural Elephant Tree , and Bursera microphylla . Padre Eusebio Kino , the founder of many Spanish missions in the Sonoran Desert , explored here in 1698 and several times later. NASA sent astronauts here starting in 1965 for geologic training, given

3828-479: The opening of the Salton Trough and the Gulf of California . The eastern margin of the Gran Desierto abuts the Cenozoic volcanic complex of the Sierra Pinacate , a composite volcanic field covering more than 1,800 square kilometres (690 sq mi) with a summit elevation of 1,206 metres (3,957 ft). Aeolian sands have climbed onto many of the western slopes of the Sierra Pinacate, defining

3894-495: The present day. The central portion of the nearby Salton Trough is more than 70 metres (230 ft) below sea level ; it is protected from marine embayment only by the natural dike of the Colorado River Delta . Ongoing tectonic activity modifies the Gran Desierto today. The southernmost extension of the San Andreas fault system, the Cerro Prieto Fault , passes directly through the area before continuing offshore into

3960-705: The present-day Colorado delta, another from the area of the paleo-delta between El Golfo and Salina Grande, and a third to the area of present-day Puerto Peñasco . Rusnak reported on sonar soundings which discovered the valleys and also describe two elongate depressions, each about 40 kilometres (25 mi) in length, into which the valley networks terminate at a depth of approximately 180 metres (590 ft) below sea level. Those incised valley systems were also interpreted as fluvial in origin. 31°57′N 114°08′W  /  31.95°N 114.14°W  / 31.95; -114.14 Pinacate Peaks The Pinacate Peaks ( Sierra Pinacate , O'odham : Cuk Doʼag ) are

4026-526: The real potential to drastically affect flora and fauna of the Mojave Desert. Agricultural development along the Colorado river , close to the Eastern boundary of the Mojave Desert, also causes habitat loss and degradation. Areas that are particularly affected by human development include Ward Valley and Riverside county. The United States military also maintains installations in the Mojave Desert, making

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4092-454: The similarity of the terrain to the lunar surface, and included training models of lunar surface equipment. Apollo 14 's Alan Shepard and Ed Mitchell , and Apollo 17 's Jack Schmitt trained here in Feb. 1970. The El Pinacate y Gran Desierto de Altar Biosphere Reserve is a biosphere reserve , in the spanish language Reserva de la Biosfera el Pinacate y Gran Desierto de Altar, managed by

4158-514: The southeastern margin of the sand sea on the Gulf of California) and decreases northward toward Yuma, Arizona (on the northwestern edge) to 62 mm (2.4 in) per year. Mid-summer highs in excess of 45 °C (113 °F) are common in the central sand sea. Mid-winter lows of less than 10 °C (50 °F) are rare. Winds are controlled in part by the position and strength of the Sonoran Low in summer, creating southerly winds, and by

4224-486: The southern and eastern sand sea, especially near the margins, have a moderately dense (up to 20%) cover of perennial low shrubs and herbs such as bursage ( Ambrosia dumosa ) and longleaf jointfir ( Ephedra trifurca ) with creosote bush ( Larrea tridentata ) in areas of thin sand cover. Palo verde / acacia / ocotillo communities occur on alluvial slopes on the northern side of the sand sea, particularly in arroyos and washes. The region's estimated total vegetation cover

4290-438: The western Pinacates; based on this work, some aeolian activity may have been present as early as 700,000 years ago, as evidenced by the dated accretionary mantles on basalt flows of the Pinacate volcanic field. Blount and Lancaster proposed that by late Pleistocene time, the Colorado River was a highly competent stream flowing through the area which is occupied today by the massive western star dune zone. The seashore at this time

4356-400: Was at least 45 kilometres (28 mi) south of its present-day location. Primary bed loads of poorly sorted gravel were deposited from present-day Yuma, Arizona to an area south of the present-day Sierra del Rosario mountains. As rifting of the Gulf of California progressed to the northwest, and uplift along the coast began, the river channel shifted westward, leaving primary bedload deposits in

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