66 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DcC. 7, 



to the overlying sandstone, to which it belongs, as I think, and not 

 to the older clay-slate formation. It is remarkable that at the 

 Tatin (so-called " goldlields ") the slate formations have the same 

 strike and are elevated at the same angle of about 70°. At the 

 month of the Umzimculu, about seven or eight miles from it, and 

 north of the young township of Murchison, the river breaks through 

 crystalline limestone of enormous thickness, but whose position 

 relative to the neighbouring strata is not clear. On both sides 

 of the valley the limestone forms precipitous walls of some 1000- 

 2000 feet, which are luxuriantly covered with vegetation. Also the 

 bottom of the river consists there of the same rock, the thickness 

 of which towards the base is not known. On the surface it only 

 covers a space of about four square miles. 



3. Table-Mountain Sandstone. — The sandstone plateaux, which 

 are so characteristic of the African landscape, lie perfectly hori- 

 zontally upon the old slate formation, and at some places upon the 

 granitic base. The sandstone, forming precipitous tableland, has 

 never been disturbed ; nowhere is a folding of the deposits visible ; 

 only fractures run through the zone, in which masses of Aphanitic 

 Diorite are seen, which have burst through the granite and slate 

 formation ; but nowhere is the sandstone raised up at an angle, or 

 folded by the greenstone. The high plateaux are covered with a 

 dense grass vegetation ; and numerous herds of cattle feed on the 

 level summits of the tableland. The soil is extremely poor, and 

 there is not even a shrub to interrupt the endless uniformity of 

 the landscape. The rivers have made their way through the beds 

 and strata of this sandstone, thus forming precipices, at some points 

 "several thousand feet in height. The sandstone shows the same litho- 

 logical peculiarities as the Table-Mountain Sandstone of the Cape, 

 after which it is named. The tops of many of the " table moun- 

 tains " of the Colony are crowned by beds of a dark basaltic green- 

 stone (fig. 1) which also possesses the same pillar-like structure as our 

 basalt. It contains fragments of quartz, granite, and gneiss. In a 

 variety of this igneous rock, from the " Great Karoo," I found small 

 traces of gold. I never found any organic remains in the sandstone 

 of the Colony itself, except in a thin soft shale, with much mica in it, 

 which seems at the Krantzkop (fig. 1) to be a bed in the sandstone, 

 from which I got some small bivalves and a finely striated Patella, 

 both too indistinct for determination. Such shale is also exposed 

 near the upper drift of the Cmkomaz river, near Richmond, and at 

 several other places in the Colony. The Sluten-Konga, Table Moun- 

 tain near Pietermaritzburg, Inanda, and Noodsberg are examples 

 of the regular-shaped table mountains of South Africa. The same 

 shales and quartz-sandstone form the Krantzkop, which drops nearly 

 vertically down to the Tugela river, about 3800 feet. The high pla- 

 teau of it is capped with melaphyre-like greenstone. The basis of 

 the Tugela valley is granite, intersected by dykes of an aphanitic 

 diorite. The slate formation, the layers of which stand almost 

 vertical, rests on the granite and is covered with the so-caUed 

 " Dooms," the celebrated mimosa vegetation of South Africa : the 

 great mass of the mountain is built up of sandstone, and crowned 



