228 EASTERN ETHIOPIA xvm 



thus, along the eastern side of the Rift Valley in its 

 deepest and most pronounced section we have the 

 Kikuyu escarpment and the Laikipia escarpment. On 

 the western side there is the Mau escarpment, the 

 Kamasia escarpment, and so on. The characters of the 

 fauna and the flora on the plateau east and w r est of 

 the valley are alike. The floor is a tract of the table- 

 land which has sunk many feet below the level of the 

 surrounding plain, but the subsidence has not affected 

 the area equally. The central portions have sunk 

 most : even in this feature of the valley abruptness 

 is its chief characteristic, for in crossing it, the traveller 

 will find himself traversing a series of terraces, some- 

 times a mile or more wide, which suddenly terminate 

 with a boundary as vertical as the wall of a fortress. 

 The faces of these scarps afford some indications of 

 the immense force which led to the formation of this 

 remarkable trough-like valley ; for they show that the 

 rock has been torn through, and the fractured surface 

 presents that same rough appearance as a sugar-loaf 

 rent in twain. The abruptness of the changes are 

 very remarkable. Gregory, in describing his journey to 

 Baringo, relates that he was walking ahead of his caravan 

 when suddenly, without the slightest warning, he found 

 himself on the edge of a precipice 1,900 feet in height. 

 For some hundreds of feet the cliff was absolutely 

 vertical. The change was so startling that for a 

 moment it made him feel giddy. 



We had a similar experience during a visit to 

 Menengai. After examining the crater we made our 

 way along its rim to the southern corner and suddenly 

 found ourselves on the verge of a vertical wall of rock, 

 absolutely bare of vegetation, black, rough, and stern. 

 We were unable to determine its altitude because our 

 aneroid had been stolen. 



The Rift Valley was probably caused by sub- 

 sidence after extensive and stupendous volcanic action. 

 The only thing I can compare it with is the Grand 



