SOUTHERN RHODESIA. 301 



by granite and other intrusive rocks and contain all the 

 gold reefs of the territory. The rocks of this division are 

 the foundations of the country. They form all the high- 

 lands and much of the lower lying districts. 

 (2) Later sediments and lavas, including the coal measures and 

 the basalts of the Victoria Falls. The larger and better 

 known portion belongs to the Karroo system, having at 

 its base the coal beds. 

 The gneissic granite usually forms a rolling bush-covered 

 country of low relief, while the massive granite builds " castle " 

 and " ball " kopjes, which form such a characteristic feature of 

 the scenery. 



Soils. — Owing to the configuration of the surface and the nature 

 of the rainfall, the extent of alluvial soil is very limited. The 

 soils which cover the widest area are the following : — 



(1) The Red Clay Soil, occurs from end to end of Southern 



Rhodesia and is derived from the greenstone schists of 

 the metamorphic group of rocks. These red clay soils 

 are poor in lime. 



(2) The Granite Soil, including the Gneiss soils, are generally 



gritty clay of a mixed grain. 



(3) The Sandstone Soils are found over wide areas in the 



northern part of the country. Wind and water have 

 played their parts in the formation. 



(4) The Black Soil is well known for its fertility. It is not 



confined to depressions (vleis), but is also found on the flat 



tops of tabular hills lying there upon the level basalt 



lavas. 



Climate. — There are two seasons, the rainy season from October 



to March, and the dry season, comprising the other six months. 



The rains are evidently due to the moisture-laden winds from the 



Indian Ocean ; they diminish in intensity on going westward 



from the ridge of high altitude running parallel with the east 



coast, from about 40 to about 20 inches. 



The dry season has very little rain, and an absolute absence of 

 rain during 4 consecutive months has been fairly frequent. On 

 the Khodesian plateau between Bulawayo and Salisbury the 

 temperature varies between 72 in January and 56 in July. On 

 the low-lying lands towards the Limpopo or the Zambesi and in 



