The desert can be understood in many ways. When there is a potential for the air to lose most of its water by evaporation than there is water, we are indeed talking about some desert condition. Hence it is important to know about wind and water in the study of deserts.
For centuries many human civilizations living in the deserts have survived facing and bracing the inhospitable living conditions brought by the vagaries of wind and water; major players not only in the formation of deserts but also in the landscape, environment, and the biomes of the deserts. While the survival and struggle for existence of multiple forms of life living in the desert needs a good adaptation to the desert conditions and environment, that of Mankind depends upon a good understanding of major players — the wind and the water — of desert as well as the will to survive within the limitations imposed by them.
This has been continuously a significant factor in the cultures and wars centering around deserts. That is because what is important for mankind is right beneath the surface of the deserts as well as in the routes and other resources on the surface of these deserts. The desert conditions have put a huge barrier to all the living plant and animals, while for man the same conditions have posed many challenges, in addition to just living there. It is not surprising that amidst its extremely harsh unforgiving environments a desert is also a big theater of amazingly colorful picturesque landscape that has many kinds of unique or unusual plants and animals; some highly adapted. With the focus on deserts we can see that many deserts are not really deserted at all!
I walked in a desert
And I cried:
“Ah, God, take me from this place!”
A voice said: “It is no desert.”
I cried: “ Well, but-
The sand, the heat, the vacant horizon.”
A voice said: “It is no desert..”
(The English Patient 97)
People think of deserts as vast expanses of sand, soil of reddish brown color, a sky of brilliant blue, no or very few plants like cacti, and camel. While for the most part the image a desert evokes holds good, in reality it is not exactly like that. The desert is not the quite searing, sandy place it’s often shown to be.
Only 15% of the world' s desert surface is pure sand (Parts of the Sahara and Arabia desert). The desert has an active and complex community of plants and animals referred to as desert biomes. Deserts are always dry with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Hidden within them are hydrocarbon reservoirs, evaporites, and other mineral deposits, as well as human artifacts preserved for centuries by the arid climate. They may be regions of sand or vast areas of rocks and gravel peppered with occasional plants.
A desert is really a group of deserts. Each desert has its own identity which makes it remarkably different from others. But all of them share a basic theme-dryness; caused by an interplay of paucity of moisture and unbridled temperatures. Michael Ondaatje characterizes the paucity of water in these lines:
“Still, today it is water who is the stranger here. Water is the exile, carried back in cans and flasks, the ghost between your hands and your mouth ” (The English Patient, 255.)
Dry areas created by global circulation patterns contain most of the deserts on the Earth. Most deserts occur within two belts; one between latitudes 20 and 30 N and another between latitudes 20 and 30 S. This distribution is a function of the global directions of wind flows; these two belts are always characterized by high atmospheric pressures, where subsiding air is warmed up as it sinks producing low humidity. However, not all deserts lie within these two belts, which in turn leads us to identify different types of deserts. Such deserts are not restricted by latitude, longitude, or elevation. They occur from areas close to the poles down to areas near the Equator. The People's Republic of China has one of the highest deserts, the Qaidam Depression, that is 2,600 meters above sea level, as well as one of the lowest deserts, the Turpan Depression, that is 150 meters below sea level. Areas receiving less than 25 cm/year of rainfall are considered "arid lands" and qualify for the definition of "desert", whereas areas receiving between 25 and 50 cm/year are "semi-arid", and may at times be considered "deserts". Most deserts are characterized by temperatures in the range of -30 to 55°C. The daytime air temperature can reach 58oC (136oF) in the Sahara. Soil temperature may reach 80oC (176oF). For half a year, the average temperature of the Mongolian desert is below the freezing point. In Antarctica, considered desert, as this area receives a limited amount of precipitation, the winter mean temperature is -30oC (41oF).
Generally deserts can be classified into five types: Subtropical, Continental, Rain shadow, Coastal and Polar.
(a) Subtropical deserts: These are deserts located in belts of descending dry air between latitudes 20 and 30 N and S of the equator. Examples include the Sahara, the Arabian desert, the Great Australian desert and the Kalahari desert.
(b) Continental deserts: These are deserts that occur in the continental interiors, far from sources of moisture. Examples include the Gobi desert in China.
(c) Rain Shadow deserts: These are deserts located on the lee sides (sides protected from wind) of mountain chains, which act as barriers between such deserts and oceans. Moist air flowing inland therefore does not reach these areas as they are "blocked" by the mountain causing precipitation on the side of the mountain facing the ocean. Examples include deserts behind the Sierra Nevada and Cascade mountains in the western U.S.A.
(d) Coastal deserts generally are found on the western edges of continents near the Tropics of Cancer and Capricorn. These are relatively complex deserts because they are at the juncture of terrestrial, oceanic, and atmospheric systems. A coastal desert, the Atacama of South America, is the Earth's driest desert. In the Atacama (Chile) measurable rainfall is one millimeter or more of rain which may occur as infrequently as once every 5-20 years.
(e) Polar deserts: These form in polar regions where the cold air is extremely low in water vapor. Examples include the dry northern Greenland, arctic Canada, and in the ice-free valleys of Antarctica (valley region of Southern Victoria Land in Antarctica).
The geologic processes in deserts are Erosion, Transportation and Deposition. In order to understand the processes and the geo-morphological features that take place in deserts, we must first identify the various agents of weathering – erosion, transportation and deposition in deserts. These include:
(a) Winds: Wind is a turbulent stream of air that has the ability to erode, transport and deposit sediment in ways similar to the action of running water. However, unlike running water, winds are not confined to channels. Their ability to carry detritus is much more limited. Nevertheless, winds are the most important transporting agent in deserts. Winds could have velocities of up to 30 Kilometers/Hour (and in some cases 80 km/hr). To get an idea of the transporting ability of winds, a strong wind of 48 km/hr can move 1/2 a ton of sand over a meter wide strip in one day! Additionally winds affect the ground conditions directly by the amount of humidity and moisture they can sustain and carry.
(b) Torrents (flash floods): Although rainfall is very limited in deserts, short periods of heavy rainfall result in the accumulation of rain water in valleys and wadis producing flash floods. These flash floods can carry much more (and much larger) debris than winds.
(c) Groundwater: The limited amount of water from rainfall received by a desert is eventually either lost by evaporation, or percolates through loose sediments and permeable layers below the surface of the earth giving rise to groundwater. This groundwater has the ability of transporting material in solution, and may have some influence on the topography of certain areas.
(d) Heat and Cold. Heat and cold produce the least observable effect in sandy desert. In contrast, their impact is much greater in rocky deserts. When water goes into the tiny crevices and expands, the rocks are forced to split up. In hot deserts, the fragmenting force of temperature is slower. Rock surfaces reach 70oC or 80oC at midday and cool down to freezing point at midnight. Expansion under the sun and contraction at night weaken the surface layers and cause flaking.
Among these agents, torrential rains and winds have the most profound impact on evolution of desert landscape by continually causing the movement of sediment. Let us first see the role of rains or water. and then the wind.
Rain rarely falls in desert. If it does, it is not seasonal. Instead, rain usually falls in the form of sudden, violent thunderstorms. There may be several storms in a year, or none for several years. The "Average rainfall each year" is not calculated based on one year' s rainfall, but on the total rainfall in a long period of time. The rate of evaporation which is known as "Moisture Index" is also used to classify deserts. There are extremely high temperatures, low humidity and very little cloud cover. The torrential downpour in rocky deserts drains into rocky watercourses that are dry except after heavy rain. These rocky watercourses are called ‘Wadis’ which deepen the dry valleys. Heavy downpour can build up into flash flood, carrying sand, gravel and then large rocks and boulders. Thus, at the end of most wadis, there is an enormous bank of sand and stone known as ‘Alluvial Fan’. The surplus sediment from the flash flood forms muddy lakes of different size and duration. A broad alluvial apron coalescing along the mountain range is called ‘Bajada’. The mountain bases may also have sloping erosional surfaces covered with detritus with a sudden change in the slope to a relatively flat bed rock surface called ‘Pediment’.
Between wadis, there are flat plateaus of different extents called ‘Mesas’. The mesas are isolated by the continuously widened wadi. The isolated mesas then become flat-topped, step- sided island in the desert, known as a ‘Butte’. These lakes are particularly seen in Australian desert. They last long enough to breed creatures like shrimps, frogs and wildfowl. Some of the lakes formed have high salt content, which is thought to be derived from salt in the atmosphere, brought from oceanic spray. Shallow, low-bottom-gradient lakes can be moved by wind-stress over many square kilometers. When they dry up, an area of clay, silt, or sand encrusted with salt is found, forming a floor on the desert basin -- a dry lakebed known as ‘Playa’.
Permeable and porous material present below the ground level through which water flows is called ‘Aquifer’. Where a natural depression in the ground surface penetrates the aquifer, water fills this depression in the form of a lake. Such depressions in the deserts filled with water are generally called “Oases’.
Wind as a geologic agent is of interest as it plays a very important role in the visible landscape of a desert; the commonly seen sand dunes and the historically known desert- sandstorms. The weathering actions of winds also known as Eolian Erosion, include the following processes:
(a) Abrasion: This is removal of loose, fine-grained particles by the turbulent eddy action of the wind that continues as a process of wearing down the surfaces of rocks by particles carried by wind. This process is also known as "sandblasting" and "frosting". It should be noted that wind alone is not abrasive, but wind loaded with sand-sized particles and dust is.
(b) Deflation: This is the process by which loose material (mainly dust and silt) is transported by wind leaving behind coarser sediments (pebbles, cobbles and boulders) on the ground, and resulting in an overall lowering of the ground surface and the creation of large flat depressions like blowouts and desert pavements.
The erosional action of torrents, groundwater and wind consequently cause a movement or transport of the products of weathering. This takes place by:
(a) Traction. A process by which large sized particles that cannot be carried or lifted by the wind are being "dragged onto" or "rolled over" the ground by the energy of the wind.
(b) Saltation. Material carried by saltation jumps off the ground intermittently as the wind intensifies, then falls again as the velocity of the wind decreases. This material is therefore finer-grained than the "traction load" of winds. Technically saltation is downwind movement of particles in a series of jumps or skips. Saltation normally lifts sand-size particles no more than one centimeter above the ground, and proceeds at one-half to one-third the speed of the wind. A saltating grain may hit other grains that jump up to continue the saltation. The grain may also hit larger grains that are too heavy to hop, but that slowly creep forward as they are pushed by saltating grains. Surface creep accounts for as much as 25 percent of grain movement in a desert.
(c)Suspension. The suspended load of winds consists of very fine grained particles (dust-sized) known as "loess". These sediments which are carried within the turbulent flow of winds can travel long distances before being deposited.
(d) Dissolution. Flowing water (including groundwater) can carry material in solution, which is deposited or precipitated as a result of physicochemical changes taking place in these solutions.
Very interestingly, eolian erosion and transportation have been studied to a great extent. The deflation zones are composed of desert ‘Pavement’ -- a sheet like surface of rock fragments that remains after wind and water have removed the fine particles. Almost half of the Earth's desert surfaces are stony deflation zones. The rock mantle in desert pavements protects the underlying material from deflation. A dark, shiny stain, called ‘Desert Varnish’ or ‘Rock Varnish’, is often found on surfaces of some desert rocks that have been exposed at the surface for a long period of time. Manganese, iron oxides, hydroxides, and clay minerals form most varnishes and provide the shine. Deflation basins, called ‘Blowouts’, are hollows formed by the removal of particles by wind. Blowouts are generally small, but may be up to several kilometers in diameter. ‘Ventifacts’ are rocks which have been cut, and sometimes polished, by the wind-driven grains, thus creating grooves or small depressions. Sculpted landforms, called ‘Yardangs’, are up to tens of meters high and kilometers long and are forms that have been streamlined by desert winds. The famous sphinx at Giza in Egypt may be a modified yardang. Steep-sided mountains, ridges, and isolated hills that rise abruptly from adjoining plains, like rocky islands standing above the surface of a broad flat sand sea are called ‘Inselbergs’ (German for island mountain). Inselbergs form in areas of relatively homogeneous resistant rock that are surrounded by rocks more susceptible to weathering.
The study of Eolian transportation provides detailed understanding for the formation of sand storms. Eolian turbidity currents are better known as ‘Dust Storms’. Air over deserts is cooled significantly when rain passes through it. This cooler and denser air sinks toward the desert surface. When it reaches the ground, the air is deflected forward and sweeps up surface debris in its turbulence as a dust storm. Crops, people, villages, and possibly even climates are affected by dust storms. Some dust storms are intercontinental, a few may circle the globe, and occasionally they may engulf entire planets. Most of the dust carried by dust storms is in the form of silt-size particles. Deposits of this windblown silt are known as ‘Loess’. The thickest known deposit of loess, 335 meters, is on the Loess Plateau in China. In Europe and in the Americas, accumulations of loess are generally from 20 to 30 meters thick. Small whirlwinds, called ‘Dust Devils’, are common in arid lands and are thought to be related to intense local heating of the air that results in instabilities of the air mass. Dust devils may be as much as one kilometer high. Michael Ondaatje has vividly described the several windstorms in the Northern Africa:
“There is a whirlwind in southern Morocco, the aajej, against which the fellahin defend themselves with knives….The arifi, …which scorches with numerous tongues. These are permanent winds that live on the present tense” (The English Patient, 16.)
Wind-deposited materials hold clues to past as well as to present wind directions and intensities. This is the process called ‘Eolian deposition’ that helps us understand the present climate and the forces that molded it. Wind-deposited sand bodies occur as ‘Sand sheets’, “Ripples’, and ‘Dunes’. Sand sheets are flat, gently undulating sandy plots of sand surfaced by grains that may be too large for saltation. They form approximately 40 percent of eolian depositional surfaces. The Selima Sand Sheet, which occupies 60,000 square kilometers in southern Egypt and northern Sudan, is one of the Earth's largest sand sheets. The Selima is absolutely flat in some places; in others, active dunes move over its surface. Wind blowing on a sand surface ‘ripples’ the surface into crests and troughs whose long axes are perpendicular to the wind direction. The average length of jumps during saltation corresponds to the wavelength, or distance between adjacent crests, of the ripples. In ripples, the coarsest materials collect at the crests. This distinguishes small ripples from dunes, where the coarsest materials are generally in the troughs.
A “Sand Dune’ is an accumulations of sediment blown by the wind into a mound or ridge. Sand dunes can be considered mega-ripples that form when the wind blows across an obstacle (a rock or a small tree or shrub) which then causes the wind to become "streamlined", creating a protected area on the "downwind" side of this obstacle where the wind velocity is low, and where eddies occur. In this protected area, the wind drops part of its saltation load, causing it to pile up (temporarily) behind this obstacle, creating a sand dune. Sand dunes commonly reach heights of 30 meters, with some dunes reaching up to 250 meter in height. Dunes have gentle upwind slopes called ‘Stoss’, on the windward or the wind-facing side. The downwind portion of the dune, the ‘Lee Slope’, the one along which sand grains slip causing the overall movement of the dune, is also known as the "Slip Face". Dunes may have more than one slipface. The minimum height of a slipface is about 30 centimeters. Sand grains move up the dune's gentle upwind slope by saltation and creep. When particles at the brink of the dune exceed the angle of repose, they spill over in a tiny landslide or avalanche that reforms the slipface. As the avalanching continues, the dune moves in the direction of the wind.
The movement of sand dunes is very interesting. The sand accumulated behind an obstacle to form a dune becomes an obstacle itself for the blowing wind, causing the deposition of more sand grains, which results in the dune growing in height. This process continues until a certain height is reached, beyond which the lee slope is no longer stable. More grains of sand deposited on top of the dune will quickly roll down its slip face, starting a new accumulation of sand behind the original dune. As this process goes on, the sand dune moves or migrates in the downwind direction. This process is also accelerated by the wind becoming faster at the peak of the dune, thus pushing more sand grains off the slip face. As sand grains slide down the slip face of a migrating dune, they are deposited on its lee side at an angle to the horizontal surface. Sometimes a conversion of sand grains and loose sediments into a solid sedimentary rock occurs. This process known as ‘Lithification’ produces cross beds, the orientation of which can be used to infer wind direction.
There are five different types of sand dunes, depending on the nature of the desert terrain, changes in the wind directions and intensity, and the supply of sand. The most common dune that forms on the deserts is the ‘Crescentic’ or Barchan Dunes’. These crescent-shaped mounds generally are wider than long, pointing downwind. The slipface is on the dune's concave side. These occur on hard, flat desert floors in areas of constant wind direction and limited sand. They may reach a height from 1 meter to more than 30 meters. And may migrate 25 meters/year. A dune forming an asymmetrical ridge transverse to dominant wind direction is called a ‘Transverse Dune’. These dunes form under winds that blow from one direction and occur in areas with abundant sand. But they also can form by merging individual barchans. Some types of crescentic dunes move faster over desert surfaces than any other type of dune. A group of dunes moved more than 100 meters per year between 1954 and 1959 in China's Ningxia Province; similar rates have been recorded in the Western Desert of Egypt. The largest crescentic dunes on Earth, with mean crest-to-crest widths of more than 3 kilometers, are in China's Taklimakan Desert.
Straight or slightly sinuous sand ridges typically much longer than they are wide are known as “Linear Dunes’. They may be more than 160 kilometers long. Linear dunes may occur as isolated ridges, but they generally form sets of parallel ridges separated by miles of sand, gravel, or rocky interdune corridors. Some linear dunes merge to form Y-shaped compound dunes. Many form in bidirectional wind regimes. The slip faces change orientation as wind shifts direction. The long axes of these dunes extend in the resultant direction of sand movement a long, relatively straight, ridge-shaped dune.The linear dunes occur in deserts with limited sand supply where winds are variable (bi-directional).
Radially symmetrical, ‘Star Dunes’ are pyramidal sand mounds with slipfaces on three or more arms that radiate from the high central peak as high as 300 meters and the base with arms resembles a star in outline. They tend to remain fixed and accumulate in areas with multidirectional wind regimes (wind blowing from all directions). Star dunes grow upward rather than laterally. They dominate the Grand Erg Oriental of the Sahara. In other deserts, they occur around the margins of the sand seas, particularly near topographic barriers. In the southeast Badain Jaran Desert of China, the star dunes are up to 500 meters tall and may be the tallest dunes on Earth.
Oval or circular mounds that generally lack a slipface, ‘Dome Dunes’ are rare and occur at the far upwind margins of sand seas. U or V-shaped mounds of sand with convex noses trailed by elongated arms are ‘Parabolic Dunes’. Sometimes these dunes are called U-shaped, blowout, or hairpin dunes, and they are well known in coastal deserts. Unlike crescentic dunes, their crests point upwind. The elongated arms of parabolic dunes follow rather than lead because they have been fixed by vegetation, while the bulk of the sand in the dune migrates forward. The longest known parabolic dune has a trailing arm 12 kilometers long, occurring wherever winds periodically reverse direction.
‘Reversing Dunes’ are varieties of any of the above types. These dunes typically have major and minor slipfaces oriented in opposite directions. All these dune types may occur in three forms: simple, compound, and complex. Simple dunes are basic forms with a minimum number of slipfaces that define the geometric type. Compound dunes are large dunes on which smaller dunes of similar type and slipface orientation are superimposed, and complex dunes are combinations of two or more dune types. A crescentic dune with a star dune superimposed on its crest is the most common complex dune. Simple dunes represent a wind regime that has not changed in intensity or direction since the formation of the dune, while compound and complex dunes suggest that the intensity and direction of the wind has changed. Vast tracts of shifting sand are called “Sand seas’. These are found in northern and western Africa, the Arabian Peninsula, and the large desert of western China, all of which contain a variety of dune forms. The play of wind and sand dunes on the deserts appear to lack any permanency. Generally for any body living in a desert for example in deserts like Sahara except the occasional violent winds “The pattern of air movement in the desert is normally fairly consistent from one day to the next.”(Key Environments: Sahara Desert. 60.).
Another feature of eolian deposition is the formation of ‘Loess’. Loess is wind-laid dust consisting largely of silt usually far away from a desert. In an odd way, the desert earth withers or dies itself and provides a more fertile ground elsewhere. This makes loess an important resource in places where it is thick and widespread as it provides rich agricultural lands. For example. Upper Mississippi Valley, the Columbia Plateau of Washington State, the loess Plateau region of central China and much of eastern Europe. Loess has two characteristics that indicate that it was deposited by the wind. It forms a rather uniform blanket over hills and valleys alike. It contains fossils of land plants and air-breathing animals.
Having explored the physical and geological processes of deserts, let us briefly look into how desert environment has impelled the adaptations upon the community of animals (Fauna) and plants (Flora), on the deserts. In terms of ecology they together make up the Desert-Biome - a group of interdependent organisms inhabiting the same region and interacting with each other, collectively forming a biotic-community. In deserts all living things must stay in tune with rain, ready for its coming and prepared to take advantage of what it offers to life. Adaptation to the heat or cold, available water from all sources, and the retention of water or moisture is the language of natural world of deserts. ‘Survival of the fittest’ is the only grammar of this language. The spring and the summer seasons are the busiest. Deserts have an exciting parade of plant and animal life.
Most desert plants are drought or salt-tolerant. The stems and leaves of some plants lower the surface velocity of sand-carrying winds and protect the ground from erosion. Deserts typically have a plant cover that is sparse but enormously diverse. The Sonoran Desert of the American Southwest has the most complex desert vegetation on Earth. The giant saguaro cacti provide nests for desert birds and serve as "trees" of the desert. Saguaro grow slowly but may live up to 200 years. When 9 years old, they are about 15 centimeters high. After about 75 years, the cacti are tall and develop their first branches. When fully grown, saguaro are 15 meters tall and weigh as much as 10 tons. Some of them just die from frost bite before reaching their full age. They dot the Sonoran and reinforce the general impression of deserts as cacti-rich land. Although cacti are often thought of as characteristic desert plants, other types of plants have adapted well to the arid environment. They include the pea family and sunflower family. Cold deserts have grasses and shrubs as dominant vegetation. Many of the desert plants have bright flowers and, attractive leaves and stems that are aesthetically appealing.
Desert plants have developed various ways to get as much water as possible and to reduce water loss. Some store water in their leaves, roots, and stems. Other desert plants have long tap roots that penetrate the water table or branched roots to get water over a wide area. These plants anchor the soil, and control erosion. With thick waxy layer on the stems and leaves, water can be retained and the tissues are protected from strong sunshine. Some plants have pin-like leaves to reduce water loss. e.g. Barrel Cactus, Pipe cactus, Fairy Duster. Many desert plants are succulents and they store water in their swollen stems or leaves. Some desert plants are the ‘Drought Evaders’. They exist as seeds before the rain comes, and grow when it rains. They flower quickly to produce seeds and then die. There are ‘Drought Resisters’ - perennial plants that possess the abilities of storing water, locating underground water or minimizing the use of water by various measures.
There are innumerable species of insects (e.g. ant, spider, millipede, centipede, scorpion.), amphibians (e.g. frogs and turtles.), reptiles (e.g. lizards, snakes, iguanas.), birds (e.g. Road runner, gila woodpecker.), and mammals (e.g. mice, rabbits, squirrel, bats, coyote, fox, peccaries. deer, bobcat, camel, homo sapiens.) that live in deserts. Michael Ondaatje puts the struggle for existence in a desert in the following line “In the desert the tools for survival are underground” (The English Patient, 172.). These animals survive buried under the desert sand to escape from the scorching heat on the desert surface. There are some species of fish like pupfish that live in marshy backwaters of desert streams and springs (The AudubonSociety Nature guides: Deserts, 476 and slide 293). Very often when people think of mammals in desert, they usually think of camels first; the ship of the desert. Almost all of the mammalian orders have their representatives in the deserts. To avoid the heat, some small mammals live in shelters underground, where the temperature fluctuations are not as much as those on the surface. Most important of all, the maximum temperature in burrows is much lower than that on the surface. They usually come out at night to search for food and store the food in burrows. Large mammals, like gazelles, onyx, asses and camels, find their shelters in the shade of a rock or tree. Some of them lose heat by evaporation, which can only increase the staying power by 2-3oC. Of course, water must be available for sweating. They get water from waterholes and by eating plants and preys. The small mammals have greater surface area to weight ratio. They gain and lose heat quickly and thus face greater problems in maintaining an acceptable body temperature range. Any animal living in desert has to have a gut that is able to excrete almost dry faecal material and a kidney that draws minimum water from blood. There are "summer hibernators" that minimize their metabolic rate in summer to avoid water loss through respiration.
Each desert country or culture has its own names for the wind, storm and sand and even desert types, and the geologic study of deserts has added many more to it. This can be summed up in the following words of Ondaatje.
“The desert could not be claimed or owned – it was a piece of cloth carried by winds, never held down by stones, and given a hundred shifting names long before” (The English Patient, 138).
Deserts have a continuing influence of geological events of very great antiquity. They are lands of extremes, changes and mystery. Most of the desert phenomena have been explored and scientifically understood and many more research studies continue for a deeper understanding of deserts, especially in greening the deserts, harnessing the mineral resources as well as stopping the continual onslaught of desertification. Today a desert traveler, enthusiast , student and scientist must be aware of the geology, fauna and flora, soil and climate, wind and water, seasons and resources just like they were explored, understood and exploited for many centuries since the earliest human beings determined to be a part of this hostile environment in their own way.