The role played by salts in hot deserts is rarely discussed in a systematic manner. Guilhem Bourrié, geochemist and soil scientist at INRAE, has analyzed the origins and nature of these salts and demonstrated how important these salt deposits in the desert are for humans, whether they live off agriculture, livestock or, indeed, the salt trade (Volume 2, Chapter 4).
Chapter 1 of Volume 3, drafted by Joly, was edited after his demise by Yann Callot, a professor at the University Lyon 2 who is a specialist in ergs and dunes. This chapter examines the importance of wind in the desert. Wind, sometimes considered to be more emblematic of a desert than even dryness, counts among the earliest dynamics on Earth, an element that humans have not always been able to control. Indeed, this lack of understanding of wind has sometimes had disastrous consequences for certain projects (see the Green Dam in Algeria).
The final chapter in Volume 3, “Living in the desert”, was taken up by Marc Côte, Professor Emeritus at the University of Provence, who worked as a professor for 20 years at the University of Constantine. He has drawn on his deep knowledge of the land and the people of the Saharan region to present what he calls “The Desert Civilization”.
Finally, it must be noted, with great regret, that, since 2010, “geopolitical turbulences have tended to change the fundamentals, to burn away knowledge and to prevent researchers from keeping in touch with this part of space and humanity.”
Acknowledgments
Most of the illustrations were refined by Éliane Leterrier.
Yvette DEWOLF
Honorary Professor at the University Paris VII, Denis Diderot
Paris
August 2020
1 1 Professor at the University Paris VII, Denis Diderot, who spent 15 years at the Moroccan Institute of Science in Rabat.
1
Introduction: The Concept of a Desert
“You cannot get the desert into a book any more than a fisherman can haul up the sea with his nets.”
E. Abbey
1.1. All about a word
Desert is one of those familiar yet ambiguous words whose meaning changes depending on people, time and place. It is one of those words whose various meanings can change the very image one has of reality. The personality of the desert is as difficult to capture in everyday language as in the imagination or in scientific research.
The object and the idea, as well as the words to talk about them, exist in humanity’s oldest texts: Babylonian, Egyptian, Hebrew, Chinese etc. In Latinate languages, the word can be traced back to 11th Century Latin. The word first described the result (desertus: deserted, abandoned) of an act of separation (deserere: to desert, to leave). A little later, the word was used to denote a place (desertum: desert), an empty or emptied site, uninhabited or depopulated. The various forms this word has taken over the years reflect this ambiguity.
In Medieval times, hermits would retire to the desert. The term, in this context, denoted both the isolation from other people as well as the barrenness of the place, the solitude and mysticism of the situation. In the 17th Century, “deserts” chiefly evoked the idea of chosen spots that were distant and discreet, where one could “flee into a desert from the approach of humans”. It was a place that was cut off from the world, voluntarily so, as was the case at the Port-Royal-des-Champs convent1, or as a result of circumstances, as in the case of the Camisards, French Protestants who lived in an isolated region of France. This connotation of abandonment or exile persists to this day. For example, we say about someone whose words go unheeded that “he is the voice crying in the wilderness” (Isaiah 40:3) and Charles de Gaulle was abandoned politically between 1946 and 1958 in a period that came to be called his “crossing through the desert.”2 From the 18th Century onwards, however, it is the geographic sense of the word that prevails. A desert is a seemingly lifeless region, uninhabited, uncultivated, arid (from the Latin arere, to burn, to dry) and sterile due to its dryness. The 19th and 20th Centuries, in turn, saw the rise of new forms of deserts: economic and demographic deserts due to rural flight toward industrial and urban areas. Finally, “desert” is used in a psychological sense to talk about an internal state resulting from a sense of deprivation of the heart or mind.
1.2. Arriving at a definition
1.2.1. What is a desert?
Different people will have different answers to this question based on their experience and imagination.
When Fénelon3 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