EUBIDGE— SOUTH-AFRICAN EOCKS. 



47 



were deposited over a wide area, and, unlike the Torbane Hill basin, 

 with the greatest uniformity. This upper coal-basin then strikingly 

 contrasts with the unique character of the Torbane Hill basin ; and 

 greatly aids our argument that the mineral was formed under different 

 physical conditions from those of the true coal-beds. 



NOTES ON THE METAMOEPHOSIS OF EOCKS IN 

 SOUTH AFEICA. 



By Dr. E. N. Eubidge, of Port Elizabeth. 



It is near eleven years since that in travelling through Howison's 

 Poort,* one of the most picturesque of the many fine mountain passes 

 through the quartzite ranges of the eastern province of the Cape 

 Colony, my attention was drawn to a geological fact to which obser- 

 vation in other parts of the Colony has since led me to attach no 

 little importance. In the construction of the main road from Port 

 Elizabeth to Graham's Town, many deep cuttings have been made in 

 the solid quartzite rock. In many instances the rock seen in these 

 works lost its crystalline character graduall}^ and assumed that of a 

 hard blue sandstone, and at length nearly resembled the blue fossi- 

 liferous shales and sandstones of the Ecca. 



These quartzite rocks have been referred to the age of the Carbo- 

 niferous formation of Europe by Mr. Bain (Geol. Trans, vol. vii. 2nd 

 series, pp. 54 and 183), and both he and Dr. Atherstone (' Eastern Pro- 

 vince Magazine,' vol. i. p. 588) describe them as conformable with the 

 slaty rocks of the district. I have no doubt whatever that they generally 

 are so. They pass gradually into each other, and, as I have described, 

 the quartzite traced downward loses much of its siliceous character, 

 and gradually assumes that of the slate and of the Ecca rock. This 

 last is by Mr. Bain dissociated from the Carboniferous formation, and 

 made the lowermost of the Lacustrine or Karoo series, but I have the 

 following reasons for differing with him : — 



1. At the western entrance of Howison's Poort are some beds of 

 rock, intermediate in lithological character between the quartzite and 

 the Ecca beds. These contain vegetable stems which have been re- 

 cognized by many as identical with those of the Ecca. At Forester's 

 Farm, east of Graham's Town, is a blue rock, just like that of the 

 Ecca, containing the same fossils, which passes gradually into the 

 gneiss. The sandstone on the one side is in relation on the other 

 with the claystone-porphyry of Bain, as is the rock at the Ecca. 

 Near Salem, in the heart of the Carboniferous system of Bain, are 

 similar rocks with like fossils, conformable with the quartzite, 



2. The strike of the inclined rocks, quartzites, slates, and Ecca 

 rocks is throughout the province north 60° west nearly. If we draw 



Poort, a natural pass through a mountain range. 



