Dr. Rubidge on some points in the Geology of South Africa. 475 



interior to avoid the Kaffirs ; in making the journey he collected 

 largely the fossils on his route, and succeeding in jireserving them on 

 his return. 



In a plain at the foot of the Rhenosterberg, which is a branch of 

 the Sneewbergen range, he met with patches of ground strewed with 

 nodular concretions and fossil wood, probably derived from the neigh- 

 bouring mountains. These mountains are composed of horizontal 

 strata. Eight of the beds at the foot of the Rhenosterberg are sand- 

 stones, above them are four layers of calcareous grit or pebbly lime- 

 stone with other sandstones. These calcareous beds sometimes con- 

 tain bones ; but at one spot in the sandstone-rock, Mr. Stow discovered 

 and chiselled out a nearly perfect skeleton of a small reptile. Other 

 reptilian bones, and especially two small well-preserved skulls, re- 

 warded his search ; one of these belonged to a small Dicynodon, the 

 other to a little undescribed reptile. 



Mr. Stow sent numerous specimens of the nodular concretions and 

 septaria from the rocks of this place, and also specimens of the con- 

 cretional and other trappean rocks of two dykes that crossed the 

 plain. 



2. " On some points in the Geology of South Africa." By Dr. 

 R. N. Rubidge. Communicated by the President. 



The author had observed in Naraaqualand the occurrence of hori- 

 zontal siliceous beds, covering other siliceous inclined beds, the 

 silification of the latter being apparently due to the infiltration of 

 silica from the upper quartzose beds into the inclined beds below. 

 In this communication Dr. Rubidge details the evidences that he 

 observed of such a process having taken place, and points out how 

 the observations on some of the Namaqualand rocks by Mr. Bain, Mr. 

 Bell, and Dr. Atherstone, respectively, tend to support his views on 

 this point. The inclined beds of this district are gneissic, and, in 

 the instances referred to, very quartzose. 



The horizontal sandstones of this district he correlates with the 

 Table-mountain sandstones, but in them he has found only a few 

 obscure traces of fucoidal or other jjlants. 



The author then passes on to the Cape district ; and, first oftering 

 his testimony to the industry and general exactitude of Mr, Bain as 

 a geologist, he proceeds to compare Mr. Bain's section of Mitchell's 

 Pass with the section he lately made for himself on two hasty 

 journeys. 



Mr. Bain describes the indurated sandstone or quartzite of Mit- 

 chell's Pass as being at first horizontal, and then suddenly dipping 

 at a strong angle northward, so as to underlie tlie Devonian schists 

 of the Bokkeveld, at Ceres, and to divide them from the slates of the 

 Cape district. Dr. Rubidge points out the api)arent difficulty of ex- 

 plaining such an inclination of the quartzite, the slates underlying 

 both the inclined and horizontal positions not j)resenting any evi- 

 dence of a difference in dip beneath the two portions of quartzite ; 

 and he suggests that the inclined beds of quartzite have nothing 

 to do with the horizontal quartzite, except that, beiog immediately 



