xviii THE CRATP:RS OF THE RIFT VALLEY 235 



bccjiuse lions were known to lai-k iil)Out the lony- gniss, 

 and lie thought it advisable to reach Nakuvu before the 

 sun went down. 



It interested me very much to find craters existing in 

 the Rift Valley with their sides clothed with tall grass, 

 the floor of the crater occupied with a forest, and the 

 whole basin large enough to afford food and shelter for 

 herds of wild animals, some of them — rhinoceros and 

 elephant — lieing the biggest mammals living on this 

 planet to-day. 



The most common fate of the crater of an extinct 

 volcano in Europe is to become a receptacle for water. 

 Two of the best examples are Lakes Albano and Nemi 

 near Rome. It is, however, historical that toward the 

 end of the seventeenth century the crater walls of 

 Vesuvius were hung with trees and brushwood ; its floor 

 was a grassy plain on which cattle grazed and the wild 

 boar lurked in the thickets. 



Mount Elgon is an extinct volcano with a base forty 

 miles in diameter. The greatest altitude at the rim is 

 14,200 feet. The crater, eight miles in diameter, is 

 crossed by a native track from north to south. Snow 

 falls on the highest points of this mountain, but does 

 not lie long. Joseph Thomson discovered this mountain 

 in 1883 and described it as an outpost of the great 

 central lava-field of Masailand. This explorer also 

 reached the remarkable caves on the southern slope 

 which have puzzled everyone who has visited them since 

 his day. The upper slopes of Elgon are clothed with 

 dense forests formed in part of bamlxjos : the lower 

 slo})es are very fertile and bananas grow abundantly. 



There are no active volcanic signs at the southern 

 extremity of the Rift Valley ; near the equatorial section 

 of this meridional trench there are a few indications in 

 the shape of steam-vents and hot springs. There is a 

 steam-vent on Longonot, and some very active jets on 

 Donyo Buru, and one is reported on Menengai. There are 

 hot springs at the southern end of Baringo, also sulphur 



