Colorado Desert

12 Key excerpts on "Colorado Desert"

• 

  eBook - PDF

  Deserts and Desert Environments

  • Julie J Laity(Author)
  • 2009(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  The modern Mojave-Sonoran Desert boundary was established about 8000–9000 years BP, when junipers and oaks disappeared from desert lowlands (Van Devender 1990). The region surrounding the lower Colorado River Valley is termed the Colorado Desert (Yeager 1957), and is the hottest and driest part of the Sonoran Desert (Ezcurra & Rodrigues 1986). Precipitation averages 50–100 mm year − 1 near the Gulf of Califor-nia and the total vegetative cover is less than 6%. Microphyllous shrubs and ephemerals dominate the flora, with few trees or cacti (Shreve 1964; Cole 1986). To the east, the higher terrain of southwest Arizona is wetter and cooler, and is floristically more complex. The Sonoran Desert is more subtropical than other North American deserts, rarely experiencing freezing temperatures. Daily summer high temperatures of 49°C or more are not uncommon in the western half of the desert. Rainfall is more evenly distributed throughout the year than in the Chihuahuan Desert, resulting in vegetation that appears more verdant. Median winter frontal precipitation ranges from 30 mm in southeastern California to 93 mm in southeastern Arizona (Woodhouse 1997). Quasi-periodic increases in winter rainfall are associated with ENSO events (Cayan & Peterson 1989). Little rain falls in late winter, spring, and early summer, when the Sonoran Desert is affected by the eastern edge of the Pacific high-pressure cell. During high summer, monsoonal circulation results in summer thunderstorms (Ezcurra & Rodrigues 1986; R.H. Schmidt 1989). Across the Sonoran Desert, there are significant regional and elevational differences in precipitation. North America’s largest field of active sand dunes (5700 km 2 ), the Gran Desierto sand sea of northwest Sonora, lies northeast of the Gulf of California. It consists of chains and clusters of star dunes, active and relict crescentic dune forms, reversing dunes, linear and parabolic dunes, and sand sheets (Lan-caster 1995).

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  A Natural History of California

  Second Edition

  • Allan A. Schoenherr(Author)
  • 2017(Publication Date)
  • University of California Press

    (Publisher)

  It is the California portion of a much larger region known as the Sonoran Desert. This southwestern desert region encircles the Gulf of California and includes northwestern Mexico, southwestern Arizona, southeastern California, and Baja California. Much of the Californian portion lies in the Salton Trough, an elongate valley separated from the Gulf of California by the delta of the Colorado River. This is a large, closed basin with the Salton Sea at its lowest point, 274 ft (88 m) below sea level. Before 1905, the Salton Sea did not exist. It 366 california’s deserts The Colorado Desert experiences more summer precipitation than the northern deserts. Although yearly precipitation remains low, a significant portion of it falls in August and September, usually as thunderstorms. Data collected at the headquarters for Anza-Borrego Desert State Park indicate a yearly average of 6.9 in (16.9 cm). Most precipitation falls from December to March, with January the only month averaging more than 1 in (25 mm). On the average, thunderstorms in August and Sep-tember add another inch (25 mm) to the yearly total. These thunderstorms may be severe. A total of 3–5 in (8–14 cm) of rain may fall in a few hours, washing out roads, scouring washes, and uprooting trees. These storms are often local in distribution; a few miles away there may be little or no precipitation. Sandy flats and slopes in the Colorado Desert are very similar to those of the Mojave Desert. Creosote Bush dominates over most of the areas with saltbushes occurring where the soil becomes more alkaline. On upper rocky slopes, particularly on the eastern side of the Peninsular Ranges, there is a community of succulent and drought-deciduous plants known as Cactus Scrub (figure 9.1, plates 4B and 16A). There are many cacti in the Sonoran Desert, but the Colorado Desert differs from other subdivi-sions of the Sonoran by having mostly small cacti.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Desert Biology

  Special Topics on the Physical and Biological Aspects of Arid Regions

  • G. W. Brown(Author)
  • 2013(Publication Date)
  • Academic Press

    (Publisher)

  The Thar Desert, astride the border between India (states of Rajasthan and Punjab) and West Pakistan, is characterized by relatively cold, windy, dusty winter conditions. While dry and definitely arid, its aridity is not nearly as great as the Tanezrouft or Libyan areas of the Sahara or the Rub 'al Khali. In North America the subtropical deserts (see Fig. 5) are the Sonoran and the Chihuahuan. The Sonoran has its center in the state of that name in Mexico but extends northward well into Arizona and south-eastern California. The California section is sometimes set off as a distinc-tive portion, to which the name Colorado Desert has unfortunately been affixed—unfortunately, in this writer's mind, since it has no relation-ship to the state of that name and the river of the same name merely skirts its eastern boundary. To the westward, the Sonoran Desert crosses the Gulf of California to the peninsula of Baja California, where it gives way rather abruptly to the strikingly different desert of the western (Pacific) coast. In the areas relatively near to the Gulf of California, including much of the Imperial Valley of California, summer humidities run fairly high—the result of evaporation from that water body. In summer, too, invasion of air from the Gulf of Mexico occasionally brings high and oppressive humidity, followed by several days of cloudburst-type rainfall, usually of destructive proportions. Situated at higher elevations, the Chihuahuan Desert has somewhat cooler conditions, and being nearer the water source (the Gulf of Mexico) it has somewhat greater rainfall. Winters are cold and clear at night and are clear and warm in the daytime. E. OCEANIC EXTENSIONS OF THE SUBTROPICAL DESERTS At first glance it would seem that the extent of desert in the southern hemisphere is much smaller than in the northern, and this is certainly the case as far as the land areas are concerned, due to the tapering of the continents southward in the southern hemisphere.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  California Archaeology

  • Michael J. Moratto(Author)
  • 2014(Publication Date)
  • Academic Press

    (Publisher)

  When this occurred, a large freshwater lake was formed that supports rich plant and animal resources, which attracted man to its margins. When the Colorado again changed its course and flowed into the Gulf of Califor-nia, the lake evaporated forming a salt sea and then a barren playa. The California deserts are arid, with the average annual rainfall vary-ing with elevation and other factors. Throughout much of the area rain-fall is as sparse as 5 cm/year and only at few locations does it exceed 20 or 25 cm. Flowever, some locations receive less than 2.5 cm of rain annually and others, at high elevations, receive more than 25 cm of precipitation a year. The marked changes in elevation between the valley floors and the mountains also reflect changes in temperature. Through most of the low valleys and the Colorado Desert, summer temperatures hover between about 100 and 118°F in the shade. The highest recorded shade tempera-ture is 134° from Death Valley. In the mountains above 1500 m, summer temperatures are closer to 90° F and even lower at the more northern latitudes. The winters are more variable and windier than the summers. Freezing temperatures (18-22° F) are recorded yearly in the higher Mojave Desert, whereas in the Colorado Desert freezing temperatures are far less frequent. At the northern latitudes, in the Great Basin desert, the winters are more like those of the central Great Basin, with freezing weather and moderate snowfall. The vegetation of the California deserts reflects the arid environment, and the variations in rainfall and temperature result in regional dif-ferences in vegetation and rather distinctive plant communities. The creosote bush is the dominant plant type throughout the Colorado and Mojave deserts and forms uniformly monotonous cover over vast areas of mountain slopes and valleys. In desert valleys the creosote bush commu-nity surrounds riparian plant communities located where water is locally abundant.

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Deserts

  Geology and Resources

  • A. S. (Alta Sharon) Walker(Author)
  • 2014(Publication Date)
  • Perlego

    (Publisher)

  U. S. Department of the Interior / U. S. Geological Survey

  Deserts: Geology and Resources

  by A. S. Walker

  Great Sand Dunes National Monument, Colorado (photograph by John Keith).

  Great Sand Dunes National Monument, Colorado (photograph by John Keith).

  Beauty is before me

  And beauty behind me,

  Above and below me hovers the beautiful,

  I am surrounded by it,

  I am immersed in it.

  In my youth I am aware of it,

  And in old age

  I shall walk quietly

  The beautiful trail.

  from a Navajo benedictory chant describing the desert

  Cacti dominate the Sonoran Desert vegetation near Tucson, Arizona (photograph by Peter Kresan).

  Cacti dominate the Sonoran Desert vegetation near Tucson, Arizona (photograph by Peter Kresan).

  What Is a Desert?

  Approximately one-third of the Earth’s land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts—stark, sometimes mysterious worlds—have been portrayed as fascinating environments of adventure and exploration from narratives such as that of Lawrence of Arabia to movies such as “Dune.” These arid regions are called deserts because they are dry. They may be hot, they may be cold. They may be regions of sand or vast areas of rocks and gravel peppered with occasional plants. But deserts are always dry.

  Ripples on a dune in the Gran Desierto, Mexico (photograph by Peter Kresan).

  Ripples on a dune in the Gran Desierto, Mexico (photograph by Peter Kresan).

  Deserts are natural laboratories in which to study the interactions of wind and sometimes water on the arid surfaces of planets. They contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for human artifacts and fossils to be preserved. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world.

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Ecology of North America

  • Brian R. Chapman, Eric G. Bolen(Authors)
  • 2015(Publication Date)
  • Wiley

    (Publisher)

  CHAPTER 7 Deserts

  The desert has a beauty all its own, a rustic scene of something to behold. So next, when you are at the desert skirt, look passed, see more than just a bunch of dirt.

  From a poem by Lady Kathleen

  North America includes four large areas assigned to the Desert Biome (Fig. 7.1 ). The “hot deserts” – Sonoran, Mojave, and Chihuahuan – receive most of their limited precipitation as winter rainfall, whereas snowfall accounts for the majority of precipitation in the Great Basin Desert, a “cold desert.” Although united by aridity each of these deserts features a distinguishable biota, often highlighted by an indicator species (e.g., giant saguaro of the Sonoran Desert). Successional developments are not readily apparent in desert communities, although degraded sites are all too common in the wake of heavy-handed human activities. At first glance deserts seem hard and durable, but they are in fact easily damaged and slow to recover from anthropogenic activities. Heavy grazing and other distresses, and a view that deserts are as suitable for dumps as they are for lizards and cacti, are among the agents that degrade desert environments. Fortunately, state and national park systems include several outstanding desert areas, and laws protect several species of desert biota.

  Figure 7.1

  Approximate delineation of the four major deserts in North America. Illustrated by Tamara R. Sayre.

  Physical geography

  Why deserts are dry

  Deserts result from phenomena related to the dramatic reduction of airborne moisture, but these forces vary in scope; some are global, but others are regional. A simple principle governs the mechanism in each case: warm air can hold a good deal of moisture, whereas cold air cannot.

  1. At the equator, where solar radiation is greatest, warm air rises then moves to the north or south over each hemisphere. This air cools rapidly as it moves upward and releases immense quantities of moisture, creating lush zones of tropical vegetation on either side of the equator. Now greatly cooled and depleted of moisture, the air sinks to Earth’s surface at latitudes between 15° and 35° north and south of the equator. As it sinks, the already dry air undergoes adiabatic

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Climate Change in Deserts

  Past, Present and Future

  • Martin Williams(Author)
  • 2014(Publication Date)
  • Cambridge University Press

    (Publisher)

  Although not as high as the mountains of Asia or the Andes, the Rockies are high enough to have a permanent cover of snow in the north, where they reach a maximum elevation of 6,196 m (20,320 feet) on Mount McKinley in Alaska. Two 20.3 Present-day climate and causes of aridity 389 smaller ranges, the Cascades and the Sierra Nevada, run roughly parallel to the main Rockies. The two largest desert areas are the Chihuahuan Desert (450,000 km 2 ), which extends from north-central Mexico into southern New Mexico, and the Sonoran Desert (300,000 km 2 ), which extends from north-west Mexico into southern Arizona. The Sonoran Desert is bounded to the east by the Sierra Madre Occidental, and receives most of its rain from the Pacific during the summer. The Chihuahuan Desert lies between the Sierra Madre Occidental and the Sierra Madre Oriental, with most of its rainfall in summer, supplemented by sporadic tropical cyclones from the Caribbean. The smaller Mojave Desert (140,000 km 2 ) lies north-east of Los Angeles and south- west of Las Vegas, within the rain shadow of the Transverse Ranges. Precipitation occurs mainly in winter, with snow on the higher ranges. The Colorado Plateau (375,000 km 2 ) and the Great Basin (410,000 km 2 ) are also arid, although their higher elevation means that they are slightly cooler in summer than the less-elevated southern deserts. The Baja California peninsula is also very dry and extends slightly south of the Tropic of Cancer. We now consider the causes of aridity in North America and northern Mexico. 20.3 Present-day climate and causes of aridity Much of North America lies within the zone of the westerlies, but the Rockies are aligned perpendicular to these moist air masses and provide a formidable barrier to their eastward passage. As a consequence, the regions east of the Rockies are in a vast rain shadow, extending in the north from North Dakota through South Dakota, Nebraska, Kansas and Oklahoma to Texas in the south.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Design with the Desert

  Conservation and Sustainable Development

  • Richard Malloy, John Brock, Anthony Floyd, Margaret Livingston, Robert H. Webb(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  We will focus on the geological and soil characteristics of the warm deserts of central and southern Arizona as these regions have experienced significant development pressures over the past few decades. Most of the world’s deserts are located around latitude 30°N and 30°S, essentially bracketing the equatorial regions. 2 Atmospheric circulation cells cause cool, water-laden air from the equator to condense out water as they rise and move northward or southward. These now dry and warm air packets descend into the desert regions, causing even more evaporation of surface water and contributing to the dry character of the landscape (see Chapter 3). FIGURE 2.1 The Sonoran Desert in the Eagle Tail Mountains west of Phoenix, Arizona. Note the characteristic desert features of exposed bedrock mountains on the skyline surrounded by alluvial fans of sediment derived from the hillslopes in the foreground; dry washes developed on the fan surfaces; and sparse vegetation cover. (Courtesy of W.L. Stefanov.) 39 Geology and Soils in Deserts of the Southwestern United States In addition, mountain ranges (e.g., the Sierra Nevada of California) cause clouds to cool and lose water as rain as they head inland from the oceans and climb over peaks. The resulting “rain shadow” contributes to the persistence of the deserts in Arizona and Nevada by decreasing the water available for precipitation on the leeward side of the ranges (see Chapter 3). Deserts can also occur near coastlines due to cool ocean air heating up as it travels inland, leading to increased evaporation. A more detailed discussion of the character and geographic distribution of deserts appears elsewhere in this book (see Chapter 1). 2.3 Geological Processes in Deserts 2.3.1 Fundamental Geological Concepts Lithified geological materials at the Earth’s surface are products of the rock cycle .

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Mammals of Colorado, Second Edition

  • David M. Armstrong, James P. Fitzgerald, Carron A. Meaney(Authors)
  • 2010(Publication Date)
  • University Press of Colorado

    (Publisher)

  Map 1-1 ). A few of the counties are nearly natural, ecological units (e.g., Jackson, Grand, and Park counties encompass North, Middle, and South parks, respectively), but most are simply political artifacts with rectilinear boundaries.

  MAP 1-1. Counties of Colorado.

  From the standpoints of physical and biological geography, Colorado is anything but simple. The marvelous complexity of the scenery is the subject of this chapter, which describes environments of Colorado from several interrelated points of view. Geologic history and materials underlie environmental patterns. Physiography is the shape of the land, reflecting hundreds of millions of years of landscape evolution. Patterns of drainage reflect and produce the landforms. Vegetation integrates climate and geologic parent material in the development of soils. Plants and animals, fungi and microbes interact as biotic communities, integrated by symbioses, and they interact with the physical environment in ceaseless cycles of materials powered by a flow of solar energy. We observe—and seek to understand—an ecological whole of extraordinary complexity. But let us begin simply, with a little history.

  Geology and Landforms

  Colorado straddles the “backbone” of North America, the Rocky Mountains. From the mountain front, the Great Plains extend eastward toward the Missouri River. To the west lie canyons and plateaus of the Colorado Plateau and the Wyoming Basin. The juxtaposition of these major physiographic regions affects temperature, precipitation, wind patterns, and drainage.

  Colorado is the highest of the United States, with a mean elevation of 2,070 m (6,800 ft.). The lowest point is 1,021 m (3,350 ft.), east of Holly, Prowers County, where the Arkansas River exits the state, and the highest point is 4,399 m (14,433 ft.), the summit of Mount Elbert, Lake County, at the top of the Arkansas watershed. Because of these varied conditions, species richness is high.

  Sign up to read

  Learn more about book
• 

  eBook - ePub

  Colorado Water Law for Non-Lawyers

  • P. Andrew Jones, Tom Cech(Authors)
  • 2009(Publication Date)
  • University Press of Colorado

    (Publisher)

  Colorado Climate, Geology, and Hydrology

  CLIMATE AND TOPOGRAPHY

  Introduction

  The nature of a society is determined, at least in part, by the attributes of the natural setting in which it develops. To understand the story of Colorado water law, one must first explore the windswept peaks, cathedral forests, and sweeping plains that form the state’s landscape. One must meet a mountain stream swollen with snowmelt in a high meadow and follow it down the mountain, through the foothills, and across the broad plain to the horizon. One must look beneath the surface of the earth at the vast, silent formations of rock and sediment, formed in ages past, now holding vast amounts of water suspended in pores and cracks within the rocks. This chapter looks at the constraints and opportunities presented by Colorado’s climate, topography, hydrology, and geology.

  1.1 Colorado shaded relief map. Courtesy of the U. S. Geological Survey

  Colorado is a very large state—the eighth largest of the fifty U.S. states—with 104,000 square miles within its borders. Many nonresidents have a preconceived vision of Colorado as composed of wall-to-wall mountains, sparkling rivers, and snow-covered ski resorts from Julesburg to Rifle. That vision is abruptly altered as one drives along Interstate 76 in northeastern Colorado, passing vistas of sagebrush, prickly pear cactus, and unending treeless prairie. Approximately 40 percent of Colorado’s land area is located in the relatively flat Eastern High Plains. The remaining landscape is almost equally divided between the Central Mountains and the Western Plateaus. Mountains, plains, mesas, and plateaus all combine to make up Colorado (Figure 1.1 ).

  Colorado’s climate is one of extremes. For a sportsperson, a good spring day could involve a round of golf in the morning and downhill skiing in the afternoon—both at world-class resorts. What makes this possible is Colorado’s diverse climate, which is shaped by its unique location and topography. According to the Ground Water Atlas of Colorado , five major factors combine to produce different, localized climates in the state: (1) latitude, (2) distance from large bodies of water, (3) elevation, (4) topography, and (5) winter storm track position.1 Average seasonal temperature and precipitation vary tremendously across Colorado. The mile-high topography varies from a low elevation of 3,315 feet, where the Arikaree River flows out of eastern Colorado into northwestern Kansas, to a high of 14,433 feet on the peak of Mt. Elbert (almost 3 miles above sea level). Average elevation is 6,800 feet above sea level and includes fifty-three mountains with elevations of 14,000 feet or more.2

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Fire and Ecosystems

  • T.T. Kozlowski(Author)
  • 2012(Publication Date)
  • Academic Press

    (Publisher)

  The relatively small portion in the United States lies largely in south central New Mexico and southwestern Texas (see Fig. 1 ) . In addition to the area delineated on the map there are smaller but almost as typical segments in southeastern Arizona and southwestern New Mexico (Shreve, 1942). 386 ROBERT R. HUMPHREY Β. CLIMATE This is an area with great extremes in mean annual precipitation. These range from as little as 3 inches in parts of Coahuila to 12-16 inches in the higher elevations near the western and southern edges of the desert. About 65 to 80% of the rain falls during the summer months from June through September. This results in a long, 8-month dry season in which the period from January to May is exceptionally dry. The lower areas typically receive light frosts particularly during December, January, and February. The higher elevations may be sub-jected to severe freezing during this same period (Shreve, 1942). C . VEGETATION The Chihuahuan Desert is essentially an area of medium-size shrubs, few cacti, and a moderate understory of grasses at the higher elevations. Although creosotebush, ocotillo (Fouquieria splendens) , and mesquite are common both here and in the Sonoran and Mojave deserts, other shrubs that are essentially restricted to the Chihuahuan Desert provide it with its primary floristic individuality. These are principally tarbush (Flourensia cernua), sandpaperbush (Mortonia scabrella), mariola (Parthenium incanum), and whitethorn (Acacia vernicosa). The upper boundaries of the Chihuahuan Desert become indistinct because of its floristic intergradation with the desert grassland and the instability of the ecotone. Both fire and grazing appear to have played a part in the successional flexibility of this boundary.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  An Island Called California

  An Ecological Introduction to Its Natural Communities

  • Elna Bakker, Gordy Slack(Authors)
  • 2023(Publication Date)
  • University of California Press

    (Publisher)

  Average annual rainfall is from 4 to 15 inches (10-38 cm.) and mostly occurs in winter, varying from place to place and year to year. Over much of the middle des- ert, summer temperatures of 95° to 100° F. (35°-38° C.) can be expected, and night frost is common throughout the winter months. The third type drops from 2,000 feet (600 m.) to below sea level and comprises the Colorado Desert, California's part of the Sonoran Desert which extends east into Arizona and south into Mexico. Summer temperatures are often considera- bly higher than on the Mojave. Rainfall averages are somewhat lower (1 to 5 inches—2.5—13 cm.) and are extremely variable. Its topographic barriers are decisive only on the west and north. The Coast Ranges of southern California swing east from the ocean in the vicinity of Santa Barbara and, with the 288 / WASH AND OASIS exception of a few passes, form an unbroken wall until they pivot around Mount San Gorgonio and thrust south to the Mexican border. The east-west trending mountains are termed the Transverse Ranges, and they are one of the few that show such marked departure from the usual direction of most of our continental ranges. Those extending south of Mount San Ja- cinto, partner peak to the taller San Gorgonio (Old Grayback) on the other side of the pass, are called the Peninsular Ranges as they form the backbone of northern Baja California. They are the relief features that not only bound but help account for the Colorado Desert to the east. Extensions of the Transverse Ranges, the Little San Bernardino and Eagle mountains, divide the Mojave from the Colorado Desert. East of these ranges there is no topographical boundary separating the two des- erts. Though each has typical floristic components, tongues of low desert plant life lick into some southern sections of the Mojave. In general, the colder winters of the middle desert de- ter many species of the Colorado from establishing themselves farther north.

  Sign up to read

  Learn more about book