Группа авторов "Mankind and Deserts 1"

Different people will have different answers to this question based on their experience and imagination.

When FГ©nelon

(#ulink_ad9e41aa-d122-56b7-ab7f-5dce06accbf9) exclaimed, “But look! The most beautiful desert you could ever see. Do you not marvel at these streams that fall from the mountains, these steep rocks?”, he was, clearly, singing the praises of one of those wild retreats of which his contemporaries would often dream. Modern-day travel agencies celebrate a more truthful picture of a desert – bare landscapes, a sea of sand and five-star bivouacs. The Paris–Dakar Rally racers, whose tracks despoil the Saharan landscape with impunity, bring to television audiences the idea of a threatening desert: devious, enchanting and sometimes deadly! A place demanding courage and renunciation.

Indeed, the Sahara, so close to Europe and featuring in desert tales so often, is what Europeans use as the model for their concept of a desert: a vast mineral landscape, no water, no trees, sand, pebbles, nomads and camels. Majestic dunes, picturesque oases, treacherous mirages, outright fabrications and howlers – all these feature in most accounts of deserts, such as Théodore Monod’s Méharées. However, the North American conception of deserts is very different: there is the desolate Death Valley, the high plains in Arizona and Utah with their monoliths, arches, their dry rios, their candelabra cacti, their prairies, the Native Americans and their horses. In Central Asia, the deserts include the steppes, in southern Africa you have the dull sands of the Kalahari dotted with trees, and the vast white lakes, the inconstant giant rivers, the interminable shifting of the red dunes of Australia with eucalyptus, aboriginal settlements, sheep and cattle rearers, remote farms, the rabbit-proof fences, the kangaroos and their dry bush that can turn into green pastures in a rainy year.

The desert is all this and more. There are populated deserts, as in Mesopotamia and Egypt, or barren, lifeless deserts such as the Tanezrouft and Lut. There are dry deserts, such as the Libyan desert, and foggy deserts such as the Namib or Atacama deserts. And to these we must also add the frozen deserts found in high mountains and the polar regions. In fact, by this definition, the Antarctic is the largest desert in the world.

A desert is, above all, a vast region that is empty, dry and outside time. T. Monod described it as “the kingdom of absence”. It is a land of surprises, contrasts and oppositions that can occur far apart or close together, sometimes spread out over years, at others separated by barely a few hours. There is the Asian desert, where you broil in summer and freeze in winter, and there is the African desert, where all the days are torrid and all the nights are cold. There is the arid desert, containing opulent oases, while you have a desert enclosed within vegetation. There are deserts that are endlessly flat, as far as the eye can see, and there are plains with rocky islands or bleak mountains. There is the sudden downpour that breaks the monotony of waterless days, and the dry river that swells into a flood. You have the bare desert that transforms, with the rain, into a carpet of flowers. And there is the seemingly uninhabited desert – where as soon as you stop, someone pops up out of nowhere to look at you and to converse.

A desert is also a bare spot that is ideal for contemplation and spirituality, where Man finds himself alone in the face of this immensity, silence and beauty. It is the void, where all fundamental questions arise. It is the Biblical antithesis to the Promised Land. It is the site of fervor, where altars are built and sacrifices made, such as the sacrifice of Abraham; the sacred land where divinity approaches humanity, the land of Moses, Jesus, Mohammed and the Buddha. It is the chosen site for renunciation and retreat, from the medieval monks to the 19th Century Father Charles de Foucauld. It is the site of exaltation, the site of gigantic temples, as can be seen in Babylon, Egypt, Syria, Tibet and in the Andes. It was also the backdrop for adventurers and empire-builders, from Alexander the Great to Genghis Khan, and from the Incans to the conquistadors of the Andes and Mexico. It has served as the arena of war from Libya to Iraq, and the testing ground for the atomic bombs. It is fertile ground for prospectors and operators, the salt-miners of the Sahel and the gold-hunters in the Americas, as well as modern-day oil seekers. Finally, deserts have also served as an observatory for the curious, such as Ibn Battuta and Marco Polo, offered new horizons to explorers, such as CaillГ© and Barth in the Sahara, Prjevalski and Sven Hedin in Asia, Powell in the Colorado and Eyre in Australia, and been used as a research field for scholars, such as Stein in Chinese Turkestan or Monod in Mauritania.

The desert is also a land of legend, exoticism and dreams, brimming over with fantasies and received ideas. Of course, this aspect of it is slowly diminishing as scientific discoveries and analyses progress and with the increasingly widespread sharing of images from these regions. The Romantics turned the desert into a mysterious land, overwhelmed by light and heat, throwing up strange mirages and sandstorms that could bury entire caravans. It was a hellish land of thirst and wind, of silence and death, that was both fascinating and horrifying. In the colonial period, the desert was always considered a redoubtable and inhuman place, the stuff of myth and legend. It was perilous, meant for military glory (like the French Foreign Legion, whose history waxes eloquent on the legionnaire “feeling the hot sand against his skin”) or for punishment (the African battalions). Even today, several fictional deserts survive, often harsher than the real ones. Dating back to a time when those who traversed the deserts were travelers, merchants or armies (rather than explorers and tourists), these accounts are often embellished with personal impressions and adventures; many are full of exaggerations or even implausible details and many were romanticized or often deliberately falsified in order to win glory, for political reasons, or to distract the competition. And so, for the layman, the desert was a secret region, hostile and populated by unknown beings who were strange and redoubtable. Many writers, carried away by their own lyrical writing or innovations, helped spread a deformed and enduring vision of the desert. For example, there was the French writer Eugène Fromentin’s A Summer in the Sahara (which was actually about the Algerian plains) or Pierre Benoît’s The Atlantide. These dreamlike deserts, “postiches” as they were dubbed by Monod, are a stark contrast to the more realistic and sobering deserts that feature in Westerns and “atmospheric novels” of the modern age, such as the novels about the American West by T. Hillerman and E. Abbey, or A. Upfield’s Australian novels.

1.2.2.Conceptual deserts: deserts that have been experienced

Each desert, considered as an object of study, may be dissected, qualified and quantified. However, this does not result in a homogeneous and unique scientific concept of deserts. A desert cannot be reduced to a concrete, simple and universal formula. To each their own desert, which seems to them more “desert-like and true” than another’s concept. There are, therefore, physical deserts that are objective and measurable by a certain degree of aridity, and then there are psychic deserts, subjective and experienced as a sensation of emptiness and the absence (or, at least, the apparent absence) of human life, and the “true desert” is, in fact, a combination of these two. For Monod, the “true” desert is the “experienced” desert, which one has walked oneself, lived through, feared and admired.

1.3. The world of deserts

In these conditions, it is futile to try and establish a clear definition of a desert that would be applicable in all cases. However, transecting a desert (the Sahara, for instance) from its periphery to its center (or the other way around) could help in revealing the most specific characteristics of the desert state, as is found, to varying degrees, in all deserts around the world.

The characteristic that can be spotted by even the untrained eye is the rapid degradation of any green cover. If someone were flying over it, in just a few minutes the view of greenery from the plane would shift from a clear forest or savanna to a disjointed steppe until it disappears altogether. On land, however, we can see that this degradation involves a gradual decrease in both the number of individual plants as well as the number of species (biodiversity), leading to increasing homogeneity. This is compounded by the unequal distribution of vegetation, spread out on the slopes and interfluves, concentrated in the wadis and showing significant variations in vitality depending on the rainfall, with certain plants rapidly blossoming after a downpour. This decrease in vegetation is accompanied by an equal decrease in the fauna in the region, especially of the animals that are most dependent on vegetation and water.

The hydrographic disruption manifests as the rarefaction of drains and a growing anarchy in water flows. Concentrated drainage divides into independent networks that become fewer and fewer in number and less and less hierarchic, with the water finally forming isolated channels or even disappearing completely. Most channels are dry in all seasons and are only revived during a flood. Apart from the large, exorheic

(#ulink_047ae684-cb49-554d-9f2d-2e5cd5440a30) allogenous rivers, such as the Nile or the Euphrates, water flow is exclusively local and linked to precipitation, which is itself intermittent and irregular. Between channels, during the rains the surface of an interfluve may often be swept by diffuse flows, in sheets or numerous and changing gullies. All these drains, except for those along the maritime coasts, are endorheic

(#ulink_c441da22-07ba-58de-884e-ecb84fc0d4f3), that is, they lead to closed basins of all sizes, which are numerous and independent, where they are lost. There is also the extreme case of an arheic region

(#ulink_4f5de330-7056-5189-898c-3f71452a164d) where there is a complete absence of water flow.

The morphology of a desert is also formed of unique features of relief, owing to the specific conditions of the desert model. The disaggregation of hydrographic networks reduces the preeminence of valleys in a landscape. The desert is flat until it enters the mountains. The horizontal shapes or shapes with very small slopes, plains, plateaus and glacis

(#ulink_9c0eb306-9bed-5e21-9c5a-9a66d1812c04) overpower sharp reliefs or reduce them to eroded tussocks or to small isolated massifs (inselbergs

(#ulink_b6d98d72-af84-58b1-8331-b50f6d3ef348)). And everywhere you have evidence of the wind at work. The sweeping winds shave off the finest elements from the rocky floors and alluvial sheets and accumulate them into dunes, scattered or grouped together (ergs).

The scarcity of water and arable land leads to a dispersion of land use and sedentary life, with sedentary populations tending to settle around better land, or land that is less poor. Humans seek alluvial land, which is more or less regularly flooded or is, at least, irrigable using ancient and varied systems. This leads to populations, cultures and habitats (oasis) being scattered (around water bodies) or arranged in a linear manner (along a river), further accentuating the powerful impression of a void that a desert creates. A relative void, however, because although the isolated and precarious water bodies, springs or wells cannot sustain agriculture by themselves, they can sustain an active, if highly scattered, nomadic life.

To summarize, we can identify five factors that make up the concept of a desert and that characterize deserts, to varying degrees and based on various combinations of different geographic features:

1) the most general of these is aridity (see Chapter 3 (#ufcc7892e-461c-5c3c-a7bd-5e9919c90558), p. 65), an obvious aspect that is, however, difficult to define and measure, as it involves the scarcity of precipitation, intense evaporation as well as the nature of soil (substratum and superficial formations);

2) problems with water (see Volume 2, Chapters 1 (#uc52e4f55-0d27-5a86-80c3-a25105824ba4)–3 (#ufcc7892e-461c-5c3c-a7bd-5e9919c90558)) are largely dependent on the previous point. While these problems involve the modalities of flow and how these affect the landscape morphology, they also involve water inputs and water capacity in the region, as well as the various ways in which inhabitants of the region use these resources;

3) the presence of salts (see Volume 2, Chapter 4), whose nature and abundance depends on the highly varied combinations of aridity and the input of dissolved salts in water, a condition that makes the water non-potable but also serves as an essential resource. This mineral wealth can be transported by the caravans for trade;

4) the wind (see Volume 3, Chapters 1 (#uc52e4f55-0d27-5a86-80c3-a25105824ba4) and 2 (#u9120ddb8-9dd6-54da-aee2-794a1a43e415)) is omnipresent and especially strong in the desert. All along its complex paths it lifts up, transports and deposits sands and dust;

5) and finally, an essential factor is that of space, which contains all the other factors. There is, first of all, the large expanse, an inordinately vast area in some deserts. Then there is also the bareness of the biological environment. The relief forms, which depend on unique legacies which, to greater and lesser extents, are ancient. Finally, you have the inhabitants, both sedentary and nomadic, who have, over the centuries, been able to construct and maintain a veritable “desert civilization” (see Volume 3, Chapter 3 (#ufcc7892e-461c-5c3c-a7bd-5e9919c90558)).

Over the course of these volumes, we will examine these five basic factors in detail. However, we begin with an overview of the history of our exploration of the deserts.

1.4. Deserts of the world

If it is not easy to define a desert, it is even harder to establish its boundaries. Most often, we see a progressive transition from the humid to the arid and then onto the desertic. These nuances are themselves limited by fuzzy boundaries, with capes, islands and enclaves that change with seasons and the passing of the years. We can ascribe certain properties to them that are more or less measurable: climatic (the abundance of rain, indicators of aridity), hydrological (density of drainage, flow indices, endorheism, arheism), biological (plant cover, composition of the flora, adaptation to dry conditions, endemism

(#ulink_babaeaa8-9f35-5c27-b14b-0ec31124c75a)), morphological (relief, geodynamic systems) or even economic (presence or absence of cultivation, the need to use irrigation). Each of these arguments or criteria is both valid and disputable, but they are only truly meaningful when combined with the others in an overall network of interdependencies that make up the desert ecosystem.

Thus, citing a specific figure for the area covered by deserts around the world is both an illusory and approximate exercise. This being said, we can broadly say that deserts (in the broadest sense) cover about a third of the area made up by the continents, without taking into account frozen deserts. They are distributed across the globe in inter-tropical and temperate regions, along three basic axes (Figure 1.1):

1) the Afro-Asiatic Eremic diagonal

(#ulink_036fad4a-07b4-5abd-b452-8e5e10e02fe5) that includes the Sahara and the deserts in Asia;

2) the North and South American Eremic diagonals;

3) the isolated deserts in the Southern Hemisphere: Northeast Brazil, South Africa, Madagascar and Australia.

Figure 1.1.Arid regions around the world as per (Meigs 1977–1979), modified

How can it be that, in the age of air travel, widespread tourism, television and the Internet, we still so often have such a fuzzy, conventional and mythical image of the deserts? There has certainly been progress in gaining direct knowledge of the deserts, but this knowledge itself has spread very slowly and imperfectly to non-desert regions. The difficulties around entering and traveling through the desert can be blamed for this slow dissemination, as well as the risks inherent to these regions. Man has traveled across the deserts for centuries out of necessity and as a result of certain events (military, political or economic), rather than through a desire to discover or gain knowledge. The merchants and travelers would follow linear paths marked by water points. They would rarely deviate from these paths, for fear of losing themselves and dying in the desert. Modern automobiles (not counting those used in the rallies) can cover in one hour the distance that a camel would take a day to travel. Those who make these journeys today do so at a speed that allows them to grasp only the most superficial of information. Views from planes or satellite images are always difficult to decipher. Tourists, reporters and artists, who are very demanding, prefer the picturesque or sensational over banal reality. There is an increasing number of scientists in this field, but they have a very limited audience. For all of these reasons, the image that the public receives of the desert is partial and varies widely depending on the source. The varying levels of reliability of the information and the unequal distribution of this knowledge go a great way toward explaining the obscurity, mystery and legends that deserts are veiled in even today.

1.5. To know more

Birot, P. (1970). Les rГ©gions naturelles du globe. Paris: Masson.

Chenu, R. (1997). Le désert — Petite anthologie. Paris: CERF, 129 p.

CRISM, ed. (2000). Figures — Le désert. Cahiers du Centre de Recherches sur l’Image, le Symbole et le Mythe, Université de Dijon, 167 p.

Cuny, H. (1961). Les dГ©serts dans le monde. Paris: Payot.

Demangeot, J. and Bernus E. (2001). Les milieux dГ©sertiques. Paris: Armand Colin. Doucey, B., ed. (2006). Le livre des dГ©serts. Collection Bouquins. Paris: Robert Laffont, 1231 p.

Dresch, J. (1966). “La zone aride, Géographie générale.” In Encyclopédie de la Pléiade. Paris: Gallimard, pp. 712–780.

— (1982). Géographie des régions arides. Collection Le Géographe. Paris: Presses Universitaires de France. 277 pp.

Haudricourt, A. and Hédin L. (1943). L’homme et les plantes cultivées. Géographie humaine. Paris: Gallimard. 233 pp.

Hills, E.S., ed. (1966). Arid lands, a geographical appraisal. Paris, London, UNESCO, Methuen & Co. 461 pp.

Joly, F. (1957). “Les milieux arides— Définition— Extension.” In Notes marocaines, Rabat 8, pp. 15–30.

Mc Ginnies, W., Goldman, B. and Paylore P. (1968). Deserts of the world — An appraisal of research into their physical and biological environments. University of Arizona Press. 788 pp.

Meigs, P., ed. (1977–1979). Carte de la répartition mondiale des régions arides, Carte à 1/25 000 000, 1 feuille en couleurs, Notice explicative. Notes techniques Man and Biosphere 7. Paris: UNESCO. 55 pp.

Monod, T. (1937). MГ©harГ©es. Explorations au vrai Sahara. BibliothГЁque des voyages. Paris: Je sers. 300 pp.

— (1973). Les déserts. Paris: Horizons de France.

Petit-Maire, N. (1984). “Le Sahara, de la steppe au désert.” In La Recherche 160, pp. 1372–1382.

Petrov, M. (1976). Deserts of the world, New York: John Wiley & Sons Ltd. de Planhol, X. and Rognon , P. (1970). Les zones tropicales arides et subtropicales.

Paris: Armand Colin. 487 pp.

Pouquet, J. (1951). Les dГ©serts. Que-sais-je ? 500. Paris: Presses Universitaires de France.

Sorre, M. (1943). Les fondements biologiques de la géographie humaine — Essai d’une écologie de l’homme. Paris: Armand Colin.

UNESCO, ed. (1962). Les problèmes de la zone aride — Actes du colloque de Paris. — ed. (1995). Les zones arides dans les programmes de l’UNESCO. Paris: UNESCO.

Chapter written by Fernand JOLY.

1 1 (#ulink_420301a5-f55e-588c-a511-c077a7feb243) Editor’s note: The Port-Royal-des-Champs Convent, south of Paris, was, in the mid-17th Century, home to a strict and ascetic religious order (Jansenism) whose teaching focused on Original Sin and condemned involvement in any “worldly” activity.

2 2 (#ulink_420301a5-f55e-588c-a511-c077a7feb243) Translator’s note: In French, desert is also used for “wilderness”.

3 3 (#ulink_b6f9a7a9-621b-515b-8268-38624e6f9a71) Editor’s note: Fénelon, a 17th Century archbishop of Cambrai – a city in the north of France – was renowned for his eloquence. He was a champion of women’s education, an uncommon stance in those times.

4 4 (#ulink_762cda9d-0937-576b-ba38-2e03605a52ee) The term “exorheic” describes a river that drains into the sea or another water body.

5 5 (#ulink_762cda9d-0937-576b-ba38-2e03605a52ee) The term “endorheic” signifies that a body of water terminates in a closed depression.

6 6 (#ulink_762cda9d-0937-576b-ba38-2e03605a52ee) The term “arheic” describes a temporary body of water with no surface runoff at all.

7 7 (#ulink_6c6b7695-8c8e-52b3-b844-d5ec77c08785) A “glacis” is a plane or slightly concave surface, with a small slope that is less than 10°, at the foot of a steep slope.

8 8 (#ulink_6c6b7695-8c8e-52b3-b844-d5ec77c08785) An “inselberg” is an isolated hill or mountain rising abruptly from an erosion plane.

9В 9 (#ulink_24cc1d65-d9e0-570b-96f5-44ec623f9fec) Endemism is used to describe species that are unique to a particular region.

10 10 (#ulink_7a925a48-8e4b-5675-85fe-e7b63956b86a) The term “eremic” means pertaining to deserts, from the Greek ἔρημος (érèmos) = desert, solitary.

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