476 Geological Society ;— 



beneath the horizontal siliceous beds, they have by some naeans been 

 silicified from above, and thus rendered in aj)pearance only identical. 

 Taking this view, he considers that the inclined quartzite is a con- 

 formable successional portion of the schists and slates, the horizontal 

 sandstones being of younger age than any of the schistose beds, and 

 extending over them from Table Mountain to Orange River on the 

 west, and to George on the east. On the north the schists are 

 known to be of Devonian age by the fossils of the Bokkeveld, and 

 the recent discovery of a few trilobites and spii-ifers at some spots 

 in the slates of the southern districts of the Cape (near Cape St. 

 Francis, at Klein Winterhoek, and near Jeffery's Bay), are consi- 

 dered by the author as corroborative of his view, that the slates of 

 the Cape are not divisible from the schists of the Bokkeveld, but are 

 to he linked to them by the intercalated quartzites described in this 

 portion of his paper, the schistose rocks of Ceres, Cape Town, and 

 Malmesbury (Silurian and Carboniferous ? of Bain) having generally a 

 similar strike and dip. 



In the eastern province of the Cape Colony, Dr. Rubidge thinks 

 that a similar condition of silification exists in the Zuurberg range, 

 although no overlying horizontal sandstones were there seen. He 

 describes in detail a section made by himself and Mr. R. Pincher, 

 along the road from Port Elizabeth to Somerset, which shows the 

 inclined schistose beds intercalated with a band of dark felspathic 

 rock (the claystone-porphyry of Bain) lying conformably on and 

 passing into the quartzite of the Zuurberg on the south, and, 

 after some great flexures of the quartzites, a similar series of conform- 

 able schistose rocks (and a felspathic band) dips from the other side of 

 the Zuurberg in an opposite direction. Similar beds continue with 

 a diminishing dip as far as Van der Merwve's River, whence they 

 rise again to the north to beyond Bushman's River (at Gower's), 

 a little beyond which the felsjjathic band appears intercalated with 

 them. The section then becomes obscured until the Karoo beds 

 are met with near Brak River, having a slight southerly dip, and 

 probably abutting unconformably against the schists near Calla- 

 ghan's Inn. This section differs in some important features from 

 that published by Mr. Bain of the same district. 



Dr. Rubidge considers that the slaty beds flanking Zuurberg on 

 either side, and forming the synclinal trough at the Van der Merwve's 

 River, are of the same age as the quartzites of the Zuurberg, which 

 are in his opinion silicified by metamorphic influences : the interbedded 

 felspathic rock may also in his opinion be possibly of metamorphic 

 origin. 



The author follows up his argument by reference to other parallel 

 sections, and regards the plant-beds of Ecca, as well as those of the 

 Great Fish River and the Van der Merwve's River, as being of Devo- 

 nian age, and not belonging to the lower Karoo beds, regarded by Mr. 

 Bain as having a more southerly extension. Dr. Rubidge notices 

 that some members of the two formations resemble each other so 

 strongly, that sometimes it is difficult to distinguish between them. 



The plant-beds above referred to contain innumerable obscure 



