Further Studies on Trade Winds During the Glacial Cycles

Core V19-301 (south of Cape Verde Islands) has been analysed in detail for (i) size distribution of quartz grains, (ii) mineralogy, (iii) colour and organic carbon (iv) G. menardii foraminifera, and (v) total foraminifera and carbonate. These results are compared with those previously obtained on core V23-100 (north of Cape Verde Islands). It is believed that the carbonate variations can be used to establish simultaneity between the cores, and thus the following climatic data emerge: (a) During glacial stages the trade winds were more vigorous than normal for the region north of the Cape Verdes; but the wintertime Harmattan was weaker than normal for the region south of the Cape Verdes. (b) The land to the north of Dakar remained desert, and was especially arid during glacials, whereas to the south of Dakar conditions oscillated between desert during interglacials, and savannah during glacials, (c) These wind and rainfall oscillations were more rapid and less excursive at around 0.7 Ma than they were in later glacial cycles.