On the Quaternary History of African Monsoon


Book Description

This thesis is devoted to reconstruct the Quaternary history of African monsoon and its influences on suspended loads of the Nile River and dust production in Sahara. The materials used in this study come from two sites (MD90-964 in the eastern Levantine Basin and ODP Site 964 in the Ionian Sea) in the eastern Mediterranean Sea. Based on clay mineralogy, grain sizes, carbonate and Corg contents, and XRF core scanning analyses of Core MD90-964, we have reconstructed history of the Nile suspended discharges, precipitation in North Africa, and Nile paleoflood events during the last 1.75 Ma. On the basis of the planktonic foraminiferal Delta(18)O record of Core MD90-964, we have established for the first time in the eastern Mediterranean Sea a high-resolution planktonic foraminiferal (G. ruber) Delta(18)O record that penetrates the Quaternary period. The ODP Site 964 allows us to establish the variations of Saharan dust inputs to the eastern Mediterranean Sea during the last 1.5 Ma. Our results indicate that both fluvial sediments from the Nile and Saharan eolian dust inputs to the eastern Mediterranean Sea are greatly influenced by the variability of African monsoon. The glacial/interglacial cycles and other orbital-scale climatic events, such as the “Mid-Pleistocene Transition”, can also affect climate changes in North Africa to a minor extent.




Aeolian Dust and Dust Deposits


Book Description

Aeolian Dust and Dust Deposits explores the entrainment, dispersion, and deposition of aeolian dust and dust deposits, with emphasis on transport and deposition of dust derived by deflation of surface sediments and soils. Topics covered range from the mechanisms of fine-particle formation to dust sources, sinks, and rates of deposition. Dust-transporting wind systems are also discussed, along with the grain size, mineralogy, and chemical composition of aeolian dust. Comprised of nine chapters, this book begins with an overview of the general nature and significance of windborne dust as well as the importance of aeolian dust and loess. The next chapter deals with the mechanisms underlying the formation of fine particles, including glacial grinding, frost and salt weathering, and fluvial comminution. The reader is then introduced to dust entrainment, transport, and deposition, together with dust sources, sinks, and rates of deposition. Subsequent chapters focus on the implications of dust deflation, transport, and deposition; dust deposition in the oceans; and loess distribution and the thickness and morphology of loess deposits. This monograph is written primarily for research workers and advanced students in sedimentology, geomorphology, and Quaternary studies, but is also likely to be of value to soil scientists, meteorologists, planetary geologists, engineers, and others concerned with environmental management.










Tropical and sub-tropical West Africa - Marine and continental changes during the Late Quaternary


Book Description

West Africa and the eastern Atlantic stretching from Mauritania in the north to Namibia in the south offer a large latitudinal stretch incorporating nearly symmetrical climatic gradients from the Equator. On the time scale of Quaternary Glacial and Interglacial cycles, today, we possess well-documented and recently published marine sedimentary records showing changes in oceanic and atmospheric circulations and terrestrial fluxes. Deep-sea sediment records contain a wide range of palaeoenvironmental indicators like oxygen and carbon isotopes, alkenones, foraminiferal and other planktonic assemblages over time periods up to and greater than 125,000 years. These are signals of temperature and circulation shifts and allow Interglacial and Glacial comparisons on a regional and inter-hemispheric scale. However, this effort to synthesize the existing knowledge cannot yet aspire to a global modelling. Linking with terrestrial records, albeit spatially patchy and generally lacking a firm chronology, this book points to shorter time scale chronologies from lakes, marshes and river deposits. Diverse and not very wellknown literature, both French and English, is reported here. Lastly, the book records recent knowledge of the first steps of human occupation of frequently hostile environments and considers the environmental impact of ancient and modern societies.* Covers the recent studies about marine Quaternary environments off West Africa, as well as continental Quaternary environments of tropical and sub-tropical West Africa (over 10,000 to 100,000 years)* Compares the parallel between palae-oenvironmental trends according to latitudinal gradients




Third Millennium BC Climate Change and Old World Collapse


Book Description

Around 4000 years ago the advanced urban civilizations in Egypt, Mesopotamia and India suddenly collapsed. What happened? Did a prolonged drought cause the breakdown of social order? Recent discoveries from all over the world strongly support the suspected link of the collapse with climate. The volume presents the findings of more than 40 researchers and provides a review on the relevant information. It appears that a major shift of the precipitation pattern affected many parts of the world at approximately the same time, with disastrous effects on the nomadic populations of Asia, Africa and Eastern Europe. Can a similar climate shift with a serious adverse impact on society happen again? In a world facing global warming, there could be many lessons to be learned from the experiences of ancient societies.




Past Climate Variability through Europe and Africa


Book Description

This book focuses on two complementary time-scales, the Holocene (approximately the last 11,500 years) and the last glacial-interglacial cycle (approximately the last 130,000 years) to synthesize evidence of climate variability at the regional and continental scale across Europe and Africa. This is the first examination of historical climate variations at such a scale, and thus sets a benchmark for future research.




Impacts of Global Change on the Hydrological Cycle in West and Northwest Africa


Book Description

Africa is highly vulnerable to the impacts of climate change. In particular shortage of fresh water is expected to be the dominant water problem for West and Northwest Africa of the 21th century. In order to solve present and projected future problems concerning fresh water supply, a highly interdisciplinary approach is used in the book. Strategies are offered for a sustainable and future-oriented water management. Based on different scenarios, a range of management options is suggested with the aid of Information Systems and Spatial Decision Support Systems for two river catchments in Northwest and West Africa: the wadi Drâa in south-eastern Morocco and the Ouémé basin in Benin. The selected catchments are representative in the sense: "what can be learnt from these catchments for other similar catchments?




The Quaternary in the Tropics


Book Description




SI


Book Description