1870.] GBIE833ACH GEOLOGY OP NATAL. OO 



It is only visible at the lowest parts of the river-valleys and near 

 the coast, in fact wherever the river, by its erosive action, has re- 

 moved the sedimentary rocks. If we draw a straight line from the 

 Umtwalume river due north, we shall touch all those parts of the 

 country where granite and gneiss reach the surface through the 

 covering of stratified rocks. Granite, as Livingstone correctly ob- 

 serves, forms the bones of the country, which at places are seen 

 through the skin. It only forms hiUs and the bottoms of river- vaUeys. 

 The granite is mostly a fine-grained grey variety ; sometimes it 

 becomes very coarse and contains large crystals of feldspar ; alto- 

 gether it has the same appearance as the granite at the Cape, which 

 Hochstetter first described as similar to the Karlsbad granite. At 

 some places there is a red variety, in w^hich the quartz and mica nearly 

 disappear, being a mere feldspathic rock, in which decomposition 

 reaches a great depth, when it presents a kaolin-like appearance, 

 similar to that found by me at the Umzinto and at the Jfafa river. 

 Further to the south, at the Umtwalume, Ehlongeni, and Umkobe 

 rivers in Alfredia, the belt of granite becomes broader, and repre- 

 sents a distinct zone. The greatest elevation is reached by the granite 

 in the counties of Victoria and Umvoti, where the JSToodsberg group of 

 mountains and all the surrounding country, and the bottoms of the 

 valleys of the rivers IJmvoti and Tugela, in the latter very far 

 up, consist principally of this rock. I have found gneiss at several 

 places, as, for instance at the base of the Sluten-Konga (Mount of 

 Mist), at the head-w^aters of the Umtwalume, &c. ; but nowhere 

 was it practicable to map it, as the high grass vegetation rendered 

 surveying quite impossible. The granite is traversed in all directions 

 by quartz-veins, which seldom have a thickness of more than from 

 about 1 inch to 2 feet. The quartz itself is a beautiful white variety, 

 almost like glass, which, besides occurring in veins, is very frequently 

 met with in large masses, called " reefs," which usually very soon thin 

 out towards their base. These quartz masses were always a subject 

 of great interest in IN'atal, as it was thought that they would yield 

 gold in paying quantities. Such is actually the case at almost all 

 places, but not in sufficient quantities to yield a profit for crushing 

 it. At the Umzinto-river valley, after a long time occupied in 

 searching, I succeeded in finding small traces of gold in a variety 

 of grey granite, which also reminds one much of the granitite of 

 Bohemia. The alluvium there also contained gold, but only in traces, 

 and not nearly sufficient to pay any one to work at it. 



2. Mica-schists, Clay-, GliJorite-, and Talcose Slate formations. — All 

 these slate formations are to be met with at places where the gra- 

 nite base is laid bare ; and everywhere the slates stand nearly up- 

 right, at an angle of 70-75°, with a strike from north to south. 

 The clay- and talcose slates are very well seen at the Umzimculuana 

 (little Umzimculu), in the county of Alfred, and at the Tugela, at 

 the junction of this with the Umziniaty river, and also at the Ite- 

 mani, a small tributary of the Tugela. At the Umpampinioni river 

 a dark grey clay-slate, dipping at an angle of about 40° and striking 

 from south to north, possesses considerable thickness (about 200 

 feet or more). It rests on granite, and underlies and is conformable 



