232 EASTERN ETHIOPIA xvm 



level. The Kikuyu escarpment is abrupt and the 

 forest runs right up to its edge. The floor of the valley 

 resembles a narrow plain containing broken hills, sheer 

 walls of pumice, extinct and active volcanoes and 

 steam-vents, in addition to the chain of lakes. 



Among the extinct volcanoes on the floor of this 

 valley mention must be made of Longonot, Suswa, 

 and Menengai. Longonot stands at a very imposing 

 cone on the floor of the valley. Thomson climbed 

 this mountain in 1883 and found on reaching the 

 top that he was on the " sharp rim of an enormous 

 pit." It was not an inverted cone, as volcanic craters 

 frequently are, but a great circular cavity, with perfectly 

 perpendicular walls, without a break in any part, though 

 on the south-western side rose a peak several hundred 

 feet above the general level of the rim." The margin of 

 the crater is so sharp that Thomson writes that he " sat 

 astride on it with one leg dangling over the abyss 

 internally, and the other down the side of the mountain. 

 The bottom of the pit seemed quite level ; it was covered 

 with acacia trees. There were no bushes or creepers 

 growing from the walls. 



Gregory investigated this mountain in 1892 : its lower 

 part consists of a series of platforms or terraces of lava. 

 The rock is a black trachytic pumice and contains a good 

 deal of obsidian (volcanic glass). The cone is in the 

 main composed of lava. He discovered a large steam- 

 vent on the inner face of the north wall of the crater 

 and climbed the peak on the western side mentioned 

 by Thomson and found it 1,800 feet higher than the 

 rim of the crater. He mentions that at the point 

 where he reached the rim of the crater it had been 

 worn by zebras into a cinder track, and that a descent 

 could easily be made into the crater on the southern side. 

 The height of Longonot is 9,350 feet. 



Hobley has climbed the mountain ; he informed me 

 that the crater is 1,300 feet deep. Near Longonot 

 there exists a deep vertical split in the rocks and the 



