Dec. 2, 1880J 



NATURE 



103 



in the plateau, and the less metamorphosed rocks. It seems mass of the continent into granite. There is however 

 to me that this range suggests a line of weakness during some hope that more definite light will be thrown upon 

 the elevation of the continent, owing to which the neigh- 1 the question of the age of this range, as on my way 

 bouring rocks were more easily folded up and raised above back to the coast I discovered in the Usagara Mountains 

 the line of greatest pressure, which has turned the main | some much metamorphosed rocks with imperfectly pre- 



7-9oopf' 



Section of Rocks betw 



ar-es-salaam and Lake Nyassa. i. Red sandy clays; 2, Carboniferous (?) sandstones with inti 



„ ^rbetided lavas; 4. Schists, gneiss, and other hignly metamorphoied rocks; 5. Granite (ormil 



rocks and probable line of fault; 7. Clay slates with occasional felspathic rocks; 8, Volcanic porphynte 



^ive rocks ; 

 tuffs, and r 



, Carboniferous 

 ;f the interior ; 

 zglomerates. 



served fossils. A careful search would probably be re- This tract, extending to near the lakes, is marked by 



warded by the discovery of fossils which would determine undulating hills and valleys, with wide areas compara- 



the age of these rocks. lively level, where the Kaffir-like semi-nomadic tribes of 



' Leaving the metamorphic rocks of the flanking range, the Wabena, Warori, Wahehi, Wagogo, and Masai herd 



we next pass over a great stretch of granitoid rocks, their cattle, hunt, and live in a constant state of warfare. 



Section, hctivcaz. ioJcc 

 8C00 



Kj'asscL & TiawKorx-ikcL £. S: T4T 



1, Volcanic porphyrltes and tuffs ; 2 2, Clay-sIates, schists, and gneiss ; 3, Intru 



The influence which the character of the country has upon j Urori, sandy as in Ugogo, or grey clay as in Unyamwesi. 

 the habits and manners of savage tribes is here well , The vegetation varies greatly according to the nature of 

 illustrated. 1 the soil. The whole of this granitoid region is marked 



The soil formed by the degradation of this granite by the occurrence of monstrous blocks, generally rounded, 

 tract is either a stiff red clay as occurs in Ubena and and strewing the whole surface as if some great eruption 



Section, {rem S.iaS'. alcnq wayt side of ToTiq own'iJai ■ 

 > it .' f 



(i) Variegated sandstone ; (2) Intruded rocks and probable line of fault ; (3) Sandstones smashed and tilted ; (4 4) Felspathic rocks ; (5 5) Fine 

 grained brick-red sandstones with quartz pebbles : (6 6 6) Greywacke and other metamorphic rocks. 



had smashed the underlying rocks. Their presence, I Ubena and Ugogo evidences of rocks erupted through the 

 however, is not due to any such cause, the main agent '> granites were obtained. 



having been rain and carbonic acid, assisted by rapid ; Continuing our route to Nyassa over this plateau at a 



radiation acting along the joints and cracks. ! general height of about 5000 feet above the sea we are 



It may be noted that at a number of points both in confronted by a sudden rise in the ground, which forms 



