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 METAMORPHOSIS OF ROCKS IN SOUTH AFRICA.
By Dr. R. N. Rubidge, of Port Elizabeth.
It is near eleven years since that in travelling through Howison's Poort,[1] 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 observation 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 gradually, and assumed that of a hard blue sandstone, and at length nearly resembled the blue fossiliferous shales and sandstones of the Ecca.
These quartzite rocks have been referred to the age of the Carboniferous formation of Europe by Mr. Bain (Geol. Trans. vol. vii. 2nd series, pp. 54 and 183), and both he and Dr. Atherstone ('Eastern Province 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 recognized 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.
