106 R. PINCHIN ON THE GEOLOGY OF PAET 



5. A short Description of the Geology of part of the Eastern Pro- 

 vince of the Colony of the Cape of Good Hope. By R. Pinchin, 

 Esq., C.E. (Read December 3, 1873.) 



(Communicated by H. W. Bristow, Esq., F.K.S., F.G.S.) 



[Abstract *.] 



[Plate IV.] 



In this paper, which was illustrated by maps and sections, the 

 author gave the results of Dr. B-ubidge's and his own observations 

 on the geology of the above region. The two principal sections de- 

 scribed were from Cape Saint Erancis across the Great Winterhoek 

 and Langeberg ranges to the lacustrine Triassic rocks near Jansen- 

 ville, and from Port Elizabeth to Somerset. The lowest rock in the 

 first section is the quartzite of the Great Winterhoek, which is im- 

 mediately overlain to the northward by shales and sandstones 

 containing Devonian fossils. Beds with similar fossils occur at the 

 Kromme river, Cape St. Francis, and near Uitenhage. A well-known 

 patch of horizontal Secondary strata stretches west along the Gam- 

 toos river, overlying the Enon conglomerate, as in the case of the 

 Jurassic strata of other parts of Uitenhage. The northern ranges, 

 Langeberg, Klein Winterhoek, and Zuurbergen, are regarded by the 

 author and others as formed of rocks belonging to the Carboniferous 

 series, although closely resembling those of the Great Winterhoek in 

 lithological character, except that among them are bands of the pe- 

 culiar rock described by Bain as " Clay stone-porphyry," by Wyley 

 as a " Trap- conglomerate or hardened Trap-ash," by Jones as a 

 "Trap-breccia," by Atherstonc as an " intrusive Trap," and by 

 Sutherland as a " Boulder- clay." Rubidge regarded it as a meta- 

 morphic rock ; and this view is adopted by the author, who describes 

 it as underlying and overlying the clay-shales, which always separate 

 it from the quartzite, and as passing imperceptibly into the shales. 



He says:' — "A glance at the map (PI. IV. fig. 1) shows that 

 this rock does not form a continuous band, as stated by Bain 

 (Geol. Trans. 2nd ser. vol. vii. p. 185), and more or less acquiesced 

 in by geologists since his time — but that it consists of a number 

 of longitudinal patches or strips, more or less parallel with each 

 other, and more or less parallel with the line of strike of the rocks 

 with which it is in all cases interstratified. These longitudinal 

 strips die out as mere threads in some places, and swell to a mile 

 or two miles in width in others. They die out altogether, and 

 are succeeded by other parallel strips at some little distance ; and 

 they appear split up, as it were, into double or triple nearly parallel 



* [Note. — The subject of this communication is especially referred to and 

 given in some detail in the 'Quart. Journ. Greol. Soc' vol. xv. (1858), p. 197; 

 1865, vol. xxi. p. 439 ; 1867, vol. xxiii. pp. 142, 172 ; and the ' Geologist,' 1862, 

 vol. v. pp. 47, 56, and pp. 366-372 ; and especially in the ' Eastern Province 

 Magazine,' vol. i. p. 187, with Section. — Edit. Q. J. G. S.] 



