TRANSACTIONS OF SECTION C. 383 



westerly, for the principal erosion occurred on the western slopes, and this erosion 

 is evidenced by the gravel terraces, which attain a remarkable development near 

 the town of Qena. These consist of materials which could have come only from 

 the highest portion of the Red Sea Hills, distant some 40 to 50 miles to the east 

 or north-east. The precipitation was most active where the range is highest, and 

 decreases towards the north where the mountains are lower. The decrease 

 towards the south is to be attributed more probably to an approach to the southern 

 limit of the moist current. 



Further evidences of such a westerly current are to be found in the existence 

 of calcareous tufas on the border of the eastern scarp of Kharga Oasis and else- 

 where; and that the temperature was then several degrees colder is shown by 

 the presence in the tufas of leaf-fragments of Quercua ilex and other plants 

 which do not now flourish south of Corsica and southern France. 



2. Change in Monsoon Effects during the Glacial Period.— There is evidence 

 of the enormous development of glaciers over Ruwenzori, Mount Kenia, Kiliman- 

 jaro, and the Himalayas, during the Glacial Period. The recession of the 

 glaciers in East Africa indicates that the temperature there is now about 10° to 

 12° F. warmer than during the period of maximum glaciation. 



It is known from the investigations of the Meteorological Department of India 

 that an. increased snowfall on the Himalayas in spring exercises a measurable 

 prejudicial effect on the Indian monsoon at the present day, and we may infer 

 that the enormously greater ice-covering of the Glacial Period would exercise a 

 much more powerful inhibition on the monsoon of that period. The more exten- 

 sive ice-sheet of East Africa, by preventing abnormal heating of the land in 

 summer, would act still further in the same direction, and it is extremely prob- 

 able that the monsoon current partook of the southerly displacement of the wind- 

 system referred to above. The general result would be a decreased precipitation 

 over Abyssinia, and a much reduced Sobat, Blue Nile, and Atbara, which at 

 present account for 96 per cent, of the flood proper of the Nile. 



The geological history of the Nile entirely accords with the above inferences. 

 One of the chief results of the present monsoon rainfall has been the deposit of 

 finely divided muds, brought from the Abyssinian hills, in the Nile valley. To 

 the south of Cairo these deposits are at most of 30 to 35 feet thickness, of which 

 10 feet have been laid down since the time of Ramses II. If conditions have 

 remained uniform, this would give a date fourteen thousand years ago for the 

 first deposits of alluvial muds in Egypt. Previous to this the mud-laden waters 

 of the Abyssinian Nile system did not reach Egypt, as the waters of Khor Gash 

 now fail to reach the Nile, and so geology and meteorology concur in indicating 

 a much weaker rainfall in Abyssinia during the Glacial Period. 



5. Interim Report of the Geological Photographs Committee. 



6. Report on the Preparation of a List of Characteristic Fossils. 

 See Reports, p. 118. 



7. Report on the Erratic Blocks of the British Isles. 

 See Reports, p. 101. 



Report on the Igneous and Associated Rocks of the Glensaul 

 and Lough Nafooey Areas, Cos. Mayo and Galway. 

 See Reports, p. 101. 



