534 Major Alfred St. Hill Gibbons [March 15, 



covered for the most part with acacia — Ac. horrida, Ac. giraffa, and 

 others — or in districts with the " mopani," a tree whose leaf when 

 viewed from a short distance is not unlike that of the beech in ap- 

 pearance, and whose dry dead leaves similarly cling to the tree when 

 the foliage of the succeeding year bursts. Through the Kalahari 

 desert the same class of vegetation thrives, though the mopani pre- 

 dominates. The soil here is of a light yellow sand, and to trek 

 through this inhospitable country, teams must be strong and wagons 

 lightly loaded — even then the struggling oxen, parched and half 

 choked with dust, can with difficulty draw the wagon through the 

 shifting sand at a greater rate than one mile an hour. After five 

 weeks of such continuous labour it can be well imagined with what 

 feelings the Zambesi with its 500 yards of deep clear water is 

 approached by both man and beast. 



This grand river, supplying as it does a natural boundary 

 between South and Central Africa, forms in more ways than one a 

 divisionary line. To the south the main rivers alone carry water 

 during the dry season ; to the north the smallest tributary has a 

 running stream throughout the year. The yellow light sand of the 

 Kalahari gives place to a heavy white sand in the Zambesi basin ; 

 thornless trees of varied and pleasant foliage replace the acacia and 

 mopani ; the natives differ in type and custom ; and in several cases 

 the river supplies a boundary to the habitat of fauna. Droughts are 

 of frequent occurrence in South Africa, but in Marotseland the rain- 

 fall is remarkably stable, varying but little annually from 38 inches. 



Throughout the Upper Zambesi basin the vegetation remains the 

 same in general character ; trees from 30 to 40 feet high offer good 

 shade, and the thorny undergrowth of some countries is conspicuous 

 by its absence. 



The rivers have quite a character of their own. Clear streams 

 wind between clean-cut banks through flat alluvial valleys 1 to 800 

 yards wide. These valleys are hemmed in by forest-clad undula- 

 tions, which increase in size and altitude in proportion to their 

 distance from the Zambesi River, the ground rising gradually to east 

 and west till it attains an altitude of 4000 feet and over. As the 

 Zambesi sources are approached, the soil has changed from white 

 sand to red, light clay, though the vegetation remains much the 

 same, with occasional local variations. Thus, on the watershed, at 

 a height of 5000 feet above the sea-level, bracken is common, while 

 I ate raspberries from bushes to all appearance similar to our English 

 plant. 



These red clay undulations — except where broken by the moun- 

 tainous ranges of Tanganika and Kivu — extend to the neighbourhood 

 of the Victoria Nile, when they give place to a yellow sandy clay, to 

 be in its turn replaced by the desert sand of Egypt. 



In the valley connecting Tanganika with Kivu, and thence north- 

 wards into Toro, the euphorbia and acacia predominate. In Unyoro 

 and down the Nile to the borders of the desert the acacia holds as 



