By P. Giresse
West Africa and the japanese Atlantic stretching from Mauritania within the north to Namibia within the south provide a wide latitudinal stretch incorporating approximately symmetrical climatic gradients from the Equator. at the time scale of Quaternary Glacial and Interglacial cycles, this present day, we own well-documented and lately released marine sedimentary documents displaying adjustments in oceanic and atmospheric circulations and terrestrial fluxes. Deep-sea sediment documents include a variety of palaeoenvironmental symptoms like oxygen and carbon isotopes, alkenones, foraminiferal and different planktonic assemblages through the years classes as much as and larger than 125,000 years. those are signs of temperature and movement shifts and make allowance Interglacial and Glacial comparisons on a neighborhood and inter-hemispheric scale. besides the fact that, this attempt to synthesize the prevailing wisdom can't but aspire to a world modelling. Linking with terrestrial documents, albeit spatially patchy and customarily missing a company chronology, this ebook issues to shorter time scale chronologies from lakes, marshes and river deposits. assorted and never very preferred literature, either French and English, is suggested the following. finally, the publication files contemporary wisdom of the 1st steps of human career of often adverse environments and considers the environmental effect of historic and smooth societies. * Covers the hot reports approximately marine Quaternary environments off West Africa, in addition to continental Quaternary environments of tropical and sub-tropical West Africa (over 10,000 to 100,000 years)* Compares the parallel among palaeoenvironmental tendencies in line with latitudinal gradients
Read Online or Download Tropical and sub-tropical West Africa: marine and continental changes during the late Quaternary PDF
Best west books
You are going to by no means fall into the vacationer traps should you go back and forth with Frommer's. it is like having a chum convey you round, taking you to the locations locals like top. Our specialist authors have already long gone all over it's possible you'll go—they've performed the legwork for you, and they are no longer afraid to inform it love it is, saving you time and cash.
Unconquerable insurgent is an exam of Hawaiian background from 1880-1904 and the political profession of part-Hawaiian, Robert W. Wilcox.
A feeling of position could be a complex topic, writes James McVey within the prologue to his new choice of essays, the way in which domestic. according to 20 years of dwelling and touring within the West, the gathering comprises essays on river working, backcountry snowboarding, fly fishing, and backpacking—all describing a number of makes an attempt to interact in significant touch with the weather of untamed nature, and to have a deep firsthand wisdom of a spot.
Tropical Africa escaped from the glaciers that coated the temperate components of the area throughout the Ice Age. The legacy is that almost all of the dad or mum fabrics of the soils of tropical Africa are previous, hugely weathered and without bases and phosphate-bearing minerals. conventional farming structures that have been rather solid and sustainable depended on lengthy fallow classes after one to 2 years of cropping to keep up the efficient means of the soils.
Extra info for Tropical and sub-tropical West Africa: marine and continental changes during the late Quaternary
1981; Schlitz, 1980). 3. Particle-Size, Mineralogy, Source Area The grain-size of mineral aerosol at Sale Island, Cape Verde, has been measured all year round. Contrarily to the concentrations, it seems that the grain-size is quite invariable which is assumed to be indicative of a nearly constant mechanism. 3-10 ~m, although the concentration varied between 20 and 600 ~tg/m3 (Prospero, 1981). In this last study, a transport of 3 ~m particles was recorded at 200-m altitude. 00 ~tm) measured through the year in South Cameroon (Pelassy, 1990).
Various alterations result from molecular diffusion, turbulent mixing and respiration of benthic organisms through the transfer. NADW is formed in the Baffin Bay, the Labrador and the Norwegian-Greenland Sea. , 1999). NADW is especially characterised by oxygen enriched nutrient depleted water masses of high CO32- and low CO2 contents whereas AABW can be described as a cold, oxygen depleted and nutrient enriched water mass of low CO32- and high CO2 contents (Reid, 1989; Boyle, 1988). The mixing Globally, the North Atlantic deep waters are warm, saline, oxygen-rich, and nutrient ones whereas the South Atlantic ones are cooler, lower in salinity and oxygen and higher in nutrients.
2. The Benguela: Large Scale Processes and Variability The present upper-level current system of the Equatorial Atlantic is mainly characterized by the northward flow of the Benguela Current, which is the eastern limb of the subtropical anticyclonic gyre. , 1996). The two branches of the Benguela Current comprise two different oceanographic regimes: the BCC transports cold waters from the winddominated coastal area northward, while the BOC transports warm water northward by geostrophic flow and constitutes the most important vehicle of the southern heat transport in the south Atlantic (see next paragraph).