CHAPTER XII 



DESCRIPTION OF THE GEOLOGICAL AND GENERAL PHYSICAL 



FEATURES {continued) 



The Koro-mbasanga Range 



As is illustrated in the accompanying profile-sketch, the 

 relatively level-topped range of Koro-tini gives place at its eastern 

 end to a broken line of mountains, of which the round-topped Koro- 

 tambu, 2,753 f eet in height, and the pinnacled Koro-mbasanga, 1 

 2,537 feet, are the highest peaks. Further east lies the broad 

 Vuinandi Gap which separates the Koro-mbasanga and Mount 

 Thurston, or Thambeyu, ranges. The twin-peaks of Mount 

 Mbatini, the highest mountain of the island, appear in the back- 

 ground in the sketch, and to the left rises Thambeyu, the second 

 highest summit. 



We enter here another complex region of mountains ; and if 

 the character of the rocks are sometimes different we shall yet 

 have to bear in mind in our interpretation of its geological features 

 the lesson derived from the examination of the Koro-tini Range. 

 Before and behind all our facts of observation lie the two 

 great periods of marine-erosion and the later ages of sub-aerial 

 denudation. 



When approached from the north, the western part of the 

 range has a rude crescentic form, and looks like the remnant of a 

 gigantic crater-cavity about two miles across. At the back rise, 

 as shown in the second of the profile-sketches, the precipitous 

 slopes of Koro-mbasanga proper ; whilst the two spurs descending 

 from it, one on the west, the Sokena spur, towards Koro-utari, the 

 other on the east, at the back of Nasawana, give the crescentic 



1 It is pointed out on p. 5 that this name is wrongly applied in the 

 Admiralty charts to Mount Mbatini, a mountain about three miles south of it. 



