Vol. 50.] GLACIAL GEOLOGY OF MOUNT KENYA. 521 



system of mere valley-glaciers, as the moraine occurs in places at 

 the foot of a rock-slope which is concentric with the peak and at 

 some distance from the mouths of the radial valleys. This terminal 

 moraine could alone have been formed by an ice-sheet which filled 

 up the whole of the valleys then in existence and spread out over 

 the whole surface of the mountain as a ' calotte.' The ice-cap 

 would have been much like that which now fills up the crater of 

 Kibo, or that which Mr. Whymper has so well described as covering 

 the dome of Chimborazo, or again that which the Rev. Maxwell Close 

 has invoked to explain the glacial phenomena of Iar-Connemara. 1 



It must be remembered, therefore, in studying the glacial evidence 

 near its lowest margin, that we have to deal with an ice-sheet and 

 not with a mere valley-glaciation. 



Former Extent. — The glaciers now terminate at a height varying 

 from 15,300-15,580 feet, or we may take the mean as 15,400 feet. 

 The old moraine at the foot of the ice-fall occurs at the level of 

 10,000 feet, while the erratics can be seen down to 9800 feet. How 

 much farther they extended it will be very difficult to determine, 

 owing to the denseness of the bamboo-jungle that covers this region 

 of the mountain. The glaciers, however, unquestionably extended 

 for at least 5400 feet below their present limit. 



Age of the Glaciation. — This is another problem that can only be 

 approximately determined. The upper set of moraines in the 

 Teleki Valley are very perfectly preserved, but there are full-sized 

 specimens of the arborescent Lobdia gregoriana, Baker til., and 

 Senecio Tcenyensis, Baker fxl., growing upon them. Though the 

 former of these may reach the height of 25-30 feet, they are pro- 

 bably of very rapid growth. The great terminal moraine is certainly 

 much older ; it is weathered, the slopes are rounded, gullies aud 

 valleys have been cut through it and the sides covered with turf ; 

 the boulders are covered with moss and the striae have been erased ; 

 the roches moutonnies have lost their polished surfaces, and only 

 the deeper grooves and the general form remain to attest their true 

 origin. Great trees, whose age must be measured by centuries, 

 grow in sheltered places on the moraine. 



There can be no reasonable doubt that the glaciation took place 

 at a date which, judging by historical standards, must have been very 

 far distant ; it was probably anterior to the introduction of the 

 tribes who now inhabit the district, and may date back to the 

 period of the maximum extension of the lakes of the East African 

 lake-chain, of which the present members are the greatly diminished 

 representatives. 



In reference to the age, it may be asked whether the glaciers 

 are now still receding. Fig. 4 (p. 522) shows the snout of the Lewis 

 glacier encircled by a Bet of terminal moraines ; the uppermost of 

 these, however, has been burst through by the glacic" ,and therefore it 

 has recently advanced. The advance, however, has bo far been a very 



1 G. H. Kinahan and Maxwell H. Close, ' The General Glaciation of Iar- 

 Connemara,' Dublin, 1872, p. 18. 



