CHAP. XII 



RECENT EARTH-MOVEMENTS 



Thus, instead of there being no new type of structure in this 

 region, and the geological facts being of wearisome monotony, 

 it teems with novel problems, and all its conditions seem different 

 from those of Europe. For the valleys are often due to rifts 

 instead of to erosion ; the mountains are sometimes formed of 

 blocks instead of by folds ; while the lava flows are on a scale that 

 shows the impossibility of measuring the universe by European 

 standards. There was yet a fourth difference which was especially 

 noticeable, as it afforded great aid in the study of the geology 

 of the district. England is an old-fashioned piece of the world ; 

 its physical features were determined long ago. Most of the 

 inequalities caused by dislocations and faults have been levelled, 



/ 



Fig. io. — Section across a " Block Mountain." (F = Faults.) 



and those that remain are mainly due to denudation and 

 erosion. But in Africa it is not so. Great earth -movements 

 have happened so recently that rock scarps, looo to 2000 feet 

 in height, still stand bare and precipitous as though formed but 

 yesterday, and straight lines and sharp angles still dominate 

 the scenery. The recent date of such earth -movements has 

 therefore rendered the physical features of the country such a 

 direct expression of its geological structure, that this can be 

 recognised in a hasty traverse. 



So intimate is the connection between the physical geo- 

 graphy of British East Africa and its geology, that it is 

 convenient to refer to the former before attempting to 

 summarise the latter. 



J 



