224 THE GEOLOGY OF BRITISH EAST AFRICA part hi 



near Kibwezi, the Iveti Mountains, the gneiss ridges of Ithamba 

 and Changabuba, Doenyo lol Daika, and the Loroghi and 

 Matthews Mountains, are the remnants in British East Africa 

 of this ancient mountain axis. 



Proceeding still farther to the west, we come to the next 

 zone — broad plains of volcanic rocks, which are the great 

 grazing lands of the nomadic tribes, and for which we may 

 adopt the Masai name of " Rangatan." The largest of these is 

 the " Kapte Plain," which extends from near the base of 

 Kilima Njaro, northward to the upper valley of the Tana. 

 Beyond this is another Rangatan, forming the high plateau of 

 Laikipia ; farther to the west is Rangatan Nyuki, or the " Red 

 Grazing Land," probably so called from the colour of the river 

 which flows through it. These Rangatan may play an impor- 

 tant part in the future of British East Africa, for, as their soil is 

 fertile and retains moisture well, and as the climate is cool and 

 bracing, they offer the best sites for European colonisation. 



The Rangatan are formed of sheets of volcanic material, 

 which occurs also piled into lofty cones. The largest of these 

 run along a line from north to south, forming the " Volcanic 

 Chain." The highest mountain of this series is Kilima Njaro 

 in German East Africa, but the largest is Kenya, 280 miles to 

 the north. Between the two occurs the line of craters of the 

 Kyulu Mountains, while the series is continued to the north 

 by Mounts Loldibo and Kulall, which link it to the lofty 

 volcanic peaks of Abyssinia. 



The last zone was originally also a highland, but it is now 

 broken by a series of north and south faults into the " Great 

 Rift Valley." 



The Geological Basis of the Seven Zones. — When we turn 

 from the superficial features of the country to its geological 

 structure, we find that the seven zones are all different in 

 composition. The coastal plain consists of raised coral reefs, 

 marine sands, shell beds, and recent alluvium, with an occa- 

 sional outlier of deposits belonging to the next zone. 



The foot plateau consists of shales and sandstones referable 

 to the middle period of geological history, though including 

 some carboniferous beds belonging to the latter part of the 

 previous era. 



The Nyika and the primitive mountain axis are both 



