232 
EASTERN ETHIOPIA 
XVIII 
level. The Kikuyu escarpment is abrupt and the 
forest runs right up to its edge. The Poor 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 v/alls. 
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 climlied 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 
