Nile Waters, Saharan Sands

August 4, 1914: British Prime Minister announces that Britain is at war with Germany. August 4, 1914: Arrest of German spy Otto Krüger by my grandfather Joseph Toye in South Wales. My grandmother Mabel Geach ranked first equal with the Senior Wrangler in Mathematics at Cambridge University in the days when women were not awarded University degrees. My mother Ethna gives the vote of thanks to Albert Einstein after she attended by mistake a lecture he gave in Berlin University in 1932. State Secretary Otto Meissner invites my mother back to Berlin in 1938 to be the governess to his daughter Hilda. My father rescues my mother from virtual house arrest at the residence of State Secretary Otto Meissner in Berlin in 1938. September 1, 1939: Following the German invasion of Poland, Britain and France declare war on Germany. My mother moves to Northern Ireland as a result of the bombing in London and South Wales, and looks after her three small sons while my father served with the Royal Engineers in France, North Africa and Italy. After the war we move to Wales (1946–7), England (1948) and then France (1950).

Move to France in 1950. Dad works in Paris for British Railways in France. Elementary school at Saint-Leu-la-Forêt an unhappy time for me. Move to La-Celle-St-Cloud. Brilliant teacher. Awarded scholarship to Lycée Hoche in Versailles. Discover the world of Egyptian antiquities in the Louvre Museum in Paris. My interest in deserts is aroused by an article on the fossil rivers of the Sahara. Leave France in late 1953.

Move to Sheffield, South Yorkshire, in late 1953. High School at King Edward VII School (Sheffield). Camping trips to Cornwall, Scotland and Ireland. Exploring Derbyshire and the Pennines. Open Exhibition in Geography to Selwyn College, Cambridge in 1959. Fieldwork in the Swiss Alps, Norway and the Macgillycuddy Reeks, County Kerry, southwest Ireland brings to life the recent glacial history of these regions. I develop an interest in recent geological history while at Cambridge.

Join Royal Military Academy Sandhurst expeditions to southeast Libyan Desert in northern summers of 1962 and 1963. Both expeditions were organised and run by Captain David Hall, Royal Engineers. We discover abundant signs of prehistoric human occupation at Jebel Arkenu ring complex in 1962 and on the Nubian Sandstone plateaux we mapped in 1963. We find evidence of multiple episodes of previously wetter climate in this now hyper-arid region. I am prompted to ask what caused these changes in climate and whether they also occurred in other deserts.

Soil surveyor and reconnaissance soil surveyor with Hunting Technical Services Limited on the Roseires Dam Project, Sudan, 1962–64. Bitten by poisonous viper one week after arriving in Sudan. Guest of the Mahdi’s grandson on Aba Island in the White Nile. Adventures along the Sudan-Ethiopian border. More snake incidents and a close encounter with a saw-scaled viper. The nomadic life of a reconnaissance soil surveyor. I start to realise that the physical and chemical properties of the soils in the Blue and White Nile valleys reflect the depositional history of those rivers, and not the present climate or the underlying geology. I decide to move to Australia to learn more about field-based soil science, a field in which Australia then led the world.

Appointed geomorphologist to the CSIRO Division of Land Research and Regional Survey in Canberra in late 1964. Take part in 1965 Land System Survey, led by plant ecologist Dr Robert Story, of the region between Arnhem Land, Darwin and Pine Creek, Northern Territory. Monitor hill slope erosion in tropical Northern Territory as part of my doctoral research at the Australian National University, Canberra, supervised by Joe Jennings. Discover the important role played by mound-building termites on soil development in tropical northern Australia. Move in 1969 to the School of Earth Sciences at Macquarie University in Sydney and teach there for the next sixteen years. Meet plant physiologist and polymath Dr Don Adamson early in 1969 and plan future joint fieldwork in the Blue and White Nile valleys of Sudan.

I join the British Army expedition to the Aïr Mountains led by Major David Hall, Royal Engineers, and travel out to Africa via Valletta in Malta and Mount Etna and Palermo in Sicily. I meet distinguished prehistoric archaeologist Professor Desmond Clark (University of California, Berkeley) at Carthage (Tunisia) on New Year’s Eve, 1969. The expedition travels by Land Rover through Tunisia and Algeria and south across the Sahara via Tamanrasset (Algeria) and Agadès (Niger), before the archaeological team drives north through the arid Aïr Mountains to the small mountain oasis of Iferouane. Desmond Clark and I set forth by camel with a Tuareg guide for Adrar Bous, an isolated mountain in the Ténéré Desert of Niger, finding Neolithic pots and stone tools on the surface as we go. On our first morning at Adrar Bous we spot a horn core of what proves to be a complete Neolithic domestic cow that died in a small swamp some five thousand years ago. We locate and excavate Early, Middle and Late Stone Ages sites together with abundant Neolithic remains, and map the shorelines of two early Holocene lakes. Andy Smith and I explore the Air Mountains by camel with a local Tuareg guide in search of prehistoric rock art. Evidence mounts of a series of wetter and drier phases extending back to at least five hundred thousand years ago associated with sporadic prehistoric human occupation in what is now the arid geographical heart of the Sahara.

I attend the Pan-African Prehistory Conference in Addis Ababa, Ethiopia in December 1971, meet the Emperor Haile Selassie, and meet many of the leading figures in African prehistory. Field trips to the Omo delta led by Yves Coppens and to the Afar Rift led by Maurice Taieb introduce me to the wealth of fossil remains in these areas. During 1974–1978 Desmond Clark, his team of archaeologists and I carry out detailed excavations in the Ethiopian Rift Valley and adjacent uplands of a variety of Neolithic and older prehistoric sites, ranging back to the Early Stone Age. We now have a detailed history of lake fluctuations and associated climatic changes in the Ethiopian Rift Valley. Close encounter with a male and female leopard. An incident during excavation of the Porc Epic Cave near Dire Dawa. The Emperor Haile Selassie is deposed and the murderous dictator Haile Mariam Mengistu takes over. Fighting breaks out in the capital and is ruthlessly suppressed. Early in 1978 one of Mengistu’s militia shoots geologist Dr Bill Morton as he was returning to Addis Ababa, and Ethiopian University students lose an outstanding geology teacher. Frances and I had left Ethiopia and returned to Sydney a few days earlier.

Don Adamson and I resume work in the lower White Nile valley in early 1972. Desmond Clark and his team of archaeologists join us in early 1973 and excavate Mesolithic, Neolithic and younger sites at Jebel Tomat, Jebel Moya and Shabona. In late 1976, Bill Morton and Frances fly in to Khartoum from Ethiopia to join Don Adamson and myself. We proceed to Nyala in Darfur to assist Dr David Parry, a reconnaissance soil surveyor with my old firm Hunting Technical Services Limited, make sense of the complex array of sediments and soils on and around Jebel Marra volcano. We find evidence of substantially wetter conditions in this region during Early Stone Age times, and are able to reconstruct a sequence of environmental changes spanning almost the last half million years. In late 1982 and early 1983, Don Adamson and I return to the site of Esh Shawal in the lower White Nile valley and uncover a flood record extending back several hundred thousand years. An outbreak of mob hysteria and potential violence at Esh Shawal circumvented by cool and decisive police action. We confirm that the last major flood event in the White Nile valley began quite suddenly 14,500 years ago with the abrupt return of the summer monsoon.

Geologist Mike Talbot and I set forth by camel in search of Wadi Azaouak in December 1973. Mike becomes the target of an amorous male camel. We discover the amazing water clarifying properties of Boscia senegalensis. We witness the impact of the drought upon the Tuareg people and learn of corruption in high places. We investigate the results of a severe rainstorm on dune erosion and develop a model of natural desertification. I learn from the local Tuareg of the destruction of the city of Darwin in tropical northern Australia by Hurricane Tracy on December 24, 1973. An attempted coup in the capital Niamey makes departure from the airport problematic.

In 1975 I spend a sabbatical year at the Laboratoire de Géologie du Quaternaire at Meudon-Bellevue just outside Paris. I share a laboratory with Françoise Gasse and discover the use of diatoms to reconstruct past changes in lake water temperature, depth and salinity. I plan the outline of a contributed volume on the Sahara and the Nile, which I later edit with Professor Hugues Faure Director of the Quaternary Geology laboratory and Professor of Geology at the University of Paris. Professor Pierre Rognon, Françoise Gasse and I investigate some of the older lake deposits in the Afar Desert of TFAI (now Djibouti) and Ethiopia. We meet Lieutenant de Barbeyrac and his tame cheetah and lunch in his fort. I visit Wadi Rumm and Petra in Jordan and learn from the local Beduin how Moses struck the rock at the present spring in Wadi Musa, which has provided fresh water for the last three thousand years.

Study leave at the University Pierre et Marie Curie, Paris in late 1978–early 1979. Instructive meetings with Théodore Monod and Professor Jean Dresch, two world authorities on the Sahara. Monod writes a foreword for The Sahara and the Nile. Fieldwork in 1979 among gypsum dunes south of the Aurès Mountains with Mohamed Ben Azzouz of the University of Constantine, Algeria. A tense encounter with some Algerian former partisans. Fieldwork in Tunisia 1979 with a team led by Professor Pierre Rognon. We decipher the complex deposits in the Wad el Akarit and in the Matmata Hills of Tunisia. The influence of wind-blown dust (loess) on runoff and sediment accumulation in local valleys becomes very evident. The Roman tradition of building stone dams to trap silt and moisture is maintained to this day in the coastal valleys of Tunisia.

I join a team of Indian and American archaeologists led by Professor G.R. Sharma (University of Allahabad) and Professor Desmond Clark (University of California, Berkeley) to work in the Son and Belan Valleys, north-central India, in 1980 and 1982. On the afternoon of February 5, 1980, geology Honours student Keith Royce and I discover volcanic ash in a cliff section on the left bank of the Son River. This was the first Quaternary ash ever found in India. Later geochemical analyses show that the ash came from a huge explosive eruption of Toba volcano in Sumatra 74,000 years ago. This eruption was probably the largest eruption in the last million years. Debate about its impact continues to rage. We excavate a series of prehistoric sites ranging in age from Neolithic back to Lower Palaeolithic. For the first time, we are able to place the prehistoric sites into a coherent stratigraphic framework. Indian geologists find remains of the Toba ash throughout India. In 2001 and 2003 Brad Pillans (Australian National University), Rajeev Patnaik (University of Chandigarh) and I help to locate and date sites in the Siwalik Beds of the Himalayan foothills with Indopithecus teeth and other fossils.

In early 1981 I join a team directed by Professor Desmond Clark to work in the middle Awash valley of the Afar desert, an area rich in fossil bones of extinct animals dating back to over four million years in age. We excavate Early Stone Age sites and possible butchery sites. Tim White identifies cut marks on the Bodo skull indicative of deliberate defleshing. This skull is about 0.5 million years old and transitional between Homo erectus and archaic Homo. We find fossil bones of probable Australopithecus afarensis several metres beneath a volcanic ash dated to 4 million years ago. I identify and sample the sediments from a lake that dried out 4 million years ago. The chief of the local Afar tribesmen explains that our lives are in danger but that he can ensure our safety, for a modest fee. I become convinced that the climate in this region was far less arid when Pliocene hominids roamed the plains over 2.5 million years ago.

In early 1983 I join Professor Virendra Misra and Professor S.N. Rajaguru in the Rajasthan desert of northwest India to work on Mesolithic and older prehistoric sites in this now semi-arid region. We excavate a deep step trench to a depth of 18.3 m and recover stone tools dating back to the very late Lower Palaeolithic. Later optical dating by Professor Ashok Singhvi indicates that the base of the trench is close to two hundred thousand years old. During that time there were twelve major climatic cycles from wet to dry, each about 20,000 years long. I enjoy meeting a group of itinerant snake catchers. Our work indicates that the Rajasthan desert was already in existence two hundred thousand years ago, and was not caused by human activities. The demise of the Indus Valley Culture was probably caused by climatic fluctuations, with desiccation setting in during the last few thousand years.

Dr Steve Brandt, University of Florida, invites me to take part in an environmental impact assessment (EIA) of the Jubba valley in Somalia in October 1988. The Somali government plan to build a dam just north of Bardera on the Jubba River in order to generate hydro-electric power for the capital Mogadishu. The Jubba rises in the Ethiopian uplands and flows south through western Somalia to the Indian Ocean. It is the only perennial river in Somalia. The EIA is needed to secure World Bank funding for the project. I set forth with two camels, a rock drill and a small team of Somalis to walk from Bardera to Luq, a river distance of about 500 km. Inspecting side valleys for alluvial deposits brought the total survey on foot to nearly 700 km. The absence of high-level alluvial silts in the side valleys within the limestone gorge traversed by the Jubba River convinces me that the proposed reservoir will never reach the level required to generate much power. I discover the two main freshwater snail vectors of the Schistosomiasis (Bilharzia) liver fluke parasite within recent flood sediments in tributary valleys, and become concerned that the proposed reservoir will spread disease through the valley. I take a dugout canoe across the river and explain my worries to a team of Somali engineers, and later to their Minister in Mogadishu. A flock of savage African bees attacks my Somali counterpart Kamil and me while we are drilling inside a limestone cave to obtain a dripstone sample for analysis. At the end of our long journey a sudden downpour blows most of our small tents down. During this downpour a small monkey adopts me. The country falls apart soon after my departure and my former camel men are killed in a raid on their village.

In 1993 climatologist Professor Bob Balling and I completed a major report for the United Nations Environment Programme and the World Meteorological Organisation on interactions between climate and desertification, as a prelude to the final drafting of the United Nations Convention to Combat Desertification. Our revised and updated report was published as a book in 1996 (M.A.J. Williams and R. J. Balling, Jr., Interactions of Desertification and Climate, Arnold, London). In July–August 1999 I took part in a joint China-Australia project investigating the causes and consequences of desertification in the arid Alashan Plateau of Inner Mongolia in northern China. Part of our brief was to suggest possible solutions in close liaison with scientists from the Desert Research Institute of the Chinese Academy of Sciences. An episode of exceptionally heavy rain in early August 1999 caused us to take refuge in a Mongolian farmhouse in the mountains and brought to an end the severe drought that had been afflicting this region for over three years. The heavy rains turned the sandy alluvium in the local valley floors to quicksands, which nearly engulfed our Mongolian guide. The local Mongolian farmers and camel herders met to celebrate the end of the drought.

On January 1, 1993 I moved from Monash University in Melbourne to the University of Adelaide in South Australia to become Director and Foundation Professor of the Mawson Graduate Centre for Environmental Studies. Soon after arriving in Adelaide, Dr Michael Atchia, who was responsible for environmental education at the United Nations Environment Programme (UNEP) HQ in Nairobi and I set up a one semester UNEP-University of Adelaide graduate certificate course in environmental management for senior government natural resource managers from Asia, the Pacific region, and parts of Africa and South America. During fieldtrips associated with this course I became interested in the recent environmental history of the arid Flinders Ranges in South Australia. Most puzzling was the evidence of an extensive late Pleistocene wetland in the central ranges during a time of peak regional aridity. The fine-grained valley-fills in the Flinders Ranges were laid down between thirty and fifteen thousand years ago, and were of similar age and origin to those I had investigated in the Matmata Hills of Tunisia in 1979. Just as in Tunisia, they were composed in large part of reworked wind-blown dust. The dust mantles on the hill slopes had led to increased infiltration and base flow and reduced runoff. The return of the intense summer rains fifteen thousand years ago led to vertical incision and a wave of gully erosion. Humans have aggravated this gully erosion during the last two hundred years but did not cause it.

In 1999 Professor Stan Ambrose, a friend and colleague from the University of Illinois at Champaign-Urbana, invited me to work with him in the West Kenya Rift. Our aim was to investigate the transition from Middle to Late Stone Age at a number of sites in this remote and beautiful area. During four field seasons (1999–2003) we achieved this aim, working closely with the local Maasai people. The stone tools and fossil bones that we excavated are still in process of analysis. An older site called Lemudong’o had an abundance of fossil bone. A bed of volcanic ash associated with the bones had an age of six million years. Dr Leslea Hjulsko, now at the University of California, Berkeley, excavated this site and published the results in full. Despite the rich fauna at the site, no hominid fossils came to light. A highlight of working in this part of Kenya was the wildlife, including Cape buffalo, lions, hyenas, jackals, baboons and anteaters. We never troubled them and they never troubled us. Being struck in the left eye by a rock proved a temporary inconvenience.

During a series of fieldtrips between 2005 and 2012, working with my own and other teams, we refine our understanding of Nile floods and extend the record of major flood episodes back over 125,000 years. Work in northern Sudan on both sides of the desert Nile reveals a sequence of wet and dry climatic intervals, of which the most recent wet interval was in the early Holocene, lasting intermittently from fifteen to five thousand years ago. An intensive programme of radiocarbon and optical (luminescence) dating in the lower Blue and White Nile valleys allows us to establish that major flood episodes in this region were synchronous with the accumulation of dark organic muds or sapropels on the floor of the eastern Mediterranean during at least the last 125,000 years. Gaps in the prehistoric record of Holocene sites in the desert Nile valley of northern Sudan show a strong link to phases of aridity and changes in flood regime. The transition from Mesolithic to Neolithic in central Sudan is also tied up with changes in local and regional climate and in Nile flow. Primary context Mesolithic sites in the lower White Nile valley are far from homogeneous and show considerable cultural variation through time.

The Romans turned the processes of hill slope erosion in the coastal valleys of North Africa to their advantage and trapped enough silt behind porous stone dams along the valley floors to enable the local farmers to grow wheat and barley, date palms and olives, just as they do today in the Matmata Hills of Tunisia. At Adrar Bous, an isolated mountain in the geographical heart of the Sahara, we were able to identify a series of stages in prehistoric occupation coinciding with wetter climatic phases extending back from Neolithic to Early Stone Age. El Niño events off the coast of Peru were harbingers of historic drought in eastern Australia, eastern China, Java, India and the Nile basin, while La Niña events in Peru led to widespread historic floods in those same regions. A task for the future in Australia is to integrate our studies of landscape evolution more thoroughly than we have yet achieved with our understanding of the evolution of the Australian flora and fauna, much of it now based upon insights from molecular biology but still lacking a firm and independent chronometric framework.