Vol. 50.] 



GLACIAL GEOLOGY OF MOUNT KENYA. 



529 



Fig. 5. — Isoharic Map, showing the low-pressure area in 

 Equatorial Africa. 



The dotted lines = mean isobars. 



the maximum glaciation, on the other hand, a high-pressure area 

 would have occurred over Kenya, Kilima Njaro, Elgon, and doubtless 

 also the Ruwenzori districts ; this would have resulted from the cold, 

 dryness of the air, abundance of snow, and inset high-level current. 

 The influence of this on the rains would be as follows : — 



(1) This high-pressure area would deflect the normal westerly 

 drift of the air along the Equator, and therefore more air would 

 reach this region from the damp forest-land of the west than does 

 so at present. 



(2) The whole region, moreover, would be subject to daily reversal 

 of the direction of the wind, and thus there would be much greater 

 local irregularities, and no sharp differentiation into wet and dry 

 seasons. The rainy seasons are now very well defined on the low- 

 lands. They occur : — 



On the coast at Lamu, Mombasa, etc., from April to August and 



for parts of December and January. 

 In South-western Kikuyu from February to May. 

 In Uganda from September to November and in April. 

 Around Basso Isarok (Lake Rudolph) in April and May. 

 In Southern Abyssinia in March and April. 



(3) The maximum rainfall now occurs in the forest zone on Mount 

 Kenya, between 7000 and 11,000 feet, though at some seasons it 

 may rise higher, just as in the Alps it is in the winter at from 

 3000 to 4000 feet, and in the summer occurs above the highest peaks. 1 

 But when the ground was higher the line of maximum rainfall 

 would not rise to the same amount, owing to the resultant lowering 



1 J. Hann, ' Die jabrliche Periocle des Regenfalles in Oesterreicb TJngarn, 

 Zeitschr. oesterreicb. Gesellscb. Meteor, vol. xv. (1880) p. 264. 



