The little-known history of how the Sahara was transformed from a green and fertile land into the largest hot desert in the world The Sahara is the largest hot desert in the world, equal in size to China or the United States. Yet, this arid expanse was once a verdant, pleasant land, fed by rivers and lakes. The Sahara sustained abundant plant and animal life, such as Nile perch, turtles, crocodiles, and hippos, and attracted prehistoric hunters and herders. What transformed this land of lakes into a sea of sands? When the Sahara Was Green describes the remarkable history of Earth’s greatest desert—including why its climate changed, the impact this had on human populations, and how scientists uncovered the evidence for these extraordinary events. From the Sahara’s origins as savanna woodland and grassland to its current arid incarnation, Martin Williams takes us on a vivid journey through time. He describes how the desert’s ancient rocks were first fashioned, how dinosaurs roamed freely across the land, and how it was later covered in tall trees. Along the way, Williams addresses many questions: Why was the Sahara previously much wetter, and will it be so again? Did humans contribute to its desertification? What was the impact of extreme climatic episodes—such as prolonged droughts—upon the Sahara’s geology, ecology, and inhabitants? Williams also shows how plants, animals, and humans have adapted to the Sahara and what lessons we might learn for living in harmony with the harshest, driest conditions in an ever-changing global environment. A valuable look at how an iconic region has changed over millions of years, When the Sahara Was Green reveals the desert’s surprising past to reflect on its present, as well as its possible future.

Reconstructing climatic changes in deserts and their margins at a variety of scales in space and time, this book draws upon evidence from land and sea, including desert dunes, wind-blown dust, river and lake sediments, glacial moraines, plant and animal fossils, isotope geochemistry, speleothems, soils, and prehistoric archaeology. The book summarises the Cenozoic evolution of the major deserts of the Americas, Eurasia, Africa and Australia, and the causes of historic floods and droughts. The book then considers the causes and consequences of desertification and proposes four key conditions for achieving ecologically sustainable use of natural resources in arid and semi-arid areas. Climate Change in Deserts is an invaluable reference for researchers and advanced students interested in the climate and geomorphology of deserts: geographers, geologists, ecologists, archaeologists, soil scientists, hydrologists, climatologists and natural resource managers.

Over the last twenty years there has been a major expansion of knowledge in the field of landforms and landforming processes of deserts. This advanced-level book provides a benchmark for the current state of science, and is written by an international team of authors who are acknowledged experts in their fields.

Drawing on rich ethnographic data as well as archaeological evidence, The Boundaries of Ancient Trade challenges long-standing conceptions of highly centralized sociopolitical and economic organization and trade along the Afar salt trail—one of the last economically significant caravan-based trade routes in the world. For thousands of years, farmers in the Tigray, Amhara, and Afar regions of Ethiopia and Eritrea have run caravans of nearly 250,000 people and pack animals annually along an eighty-mile route through both cold, high-altitude farmlands and some of the hottest volcanic desert terrain on earth. In her fieldwork, archaeologist Helina Solomon Woldekiros followed the route with her own donkey and camel caravan, observing and interviewing over 150 Arho (caravaners), salt miners, salt cutters, warehouse owners, brokers, shop owners, and salt village residents to model the political economy of the ancient Aksumite state. The first integrated ethnoarchaeological and archaeological research on this legendary route, this volume provides evidence that informal economies and local participation have played a critical role in regional trade and, ultimately, in maintaining the considerable power of the Aksumite state. Woldekiros also contributes new insights into the logistics of pack animal–based trade and variability in the central and regional organization of global ancient trade. Using a culturally informed framework for understanding the organization of the ancient salt route and its role in linking the Aksumite state to rural highland agricultural and lowland mobile pastoralist populations, The Boundaries of Ancient Trade makes a key contribution to theoretical discussions of hierarchy and more diffuse power structures in ancient states. This work generates new interest in the region as an area of global relevance in archaeological and anthropological debates on landscape, social interaction, and practice theories.

In this book, the author describes in simple, non-technical terms the adventures he has experienced during his work as an earth scientist in some of the remote parts of the arid and semi-arid world. His aim in writing this concise account of some of the work he has been involved in over the past fifty years is to try to convey to the non-specialist some of the excitement and fun involved in fieldwork in the drier regions of the world. His studies of the soils, landforms and the recent geological history of arid and semi-arid regions have taken Martin Williams to some remarkable places in Africa, Asia, Australia and the Middle East. Not only are the landscapes themselves often stunningly beautiful, but the contact with people from quite different backgrounds and cultures has been an enriching experience. His work has taken him to places far off the beaten track, whether it be the rugged mountains of Ethiopia and northern China, the sandy deserts of the Sahara and Rajasthan, or the great river valleys of Somalia, central India and the Nile. The chapters that follow are not intended to form a coherent chronological narrative, although they do appear in rough chronological order. They should rather be viewed as vignettes or brief evocative descriptions, much as in the discursive tradition of the wandering Irish storytellers. Acting on the principle that it is not necessary to be solemn to be serious, the author aims to entertain as well as to instruct.

About one-third of the Earth’s land surface experiences a desert climate, and this area supports approximately 15% of the planet’s population. This percentage continues to grow, and with this growth comes the need to acquire and apply an understanding of desert geomorphology. Such an understanding is vital in managing scarce and fragile resources and in mitigating natural hazards. This authoritative reference book is comprehensive in its coverage of the geomorphology of desert environments, and is arranged thematically. It begins with an overview of global deserts, proceeds through treatments of weathering, hillslopes, rivers, piedmonts, lake basins, and aeolian surfaces, and concludes with a discussion of the role of climatic change. Written by a team of international authors, all of whom are active in the field, the chapters cover the spectrum of desert geomorphology.