Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/691

 3. On some Points in South-African Geology. — Parts II. and III. On the Dicynodon or Karoo Formation — its Forest-zones, as shown by Sections in the Winterberg and the Stormberg (Dordrecht, Upper Kei River, and Klaas Smit's River), and its Denudation by Ice-action ; with Remarks on the Climatal changes in South Africa. By G. W. Stow, Esq., of Queenstown, South Africa.

(Communicated, with Notes, by Prof. T. Rupert Jones, F.G.S.)

[Read December 7, 1870*.]

Part II. — The Forest-zones and other Strata of the Dicynodon Formation.

In the Dicynodon (Karoo) formation† we find two or more distinct forest-zones in this eastern part of the colony. At Dordrecht (Albert), in the Upper Stormberg range, on the south of the Kaga Mountain (an offshoot of the Winterberg, in East Somerset), in the Kroome range, and in the Amatola Mountains (British Kaffraria) a thick and gritty sandstone frequently makes its appearance on the slopes of minor valleys, and on the flats at the same line of elevation ; and wherever it is exposed there is almost invariably an abundance of fossil wood. Near Greytown and the Kabousie nearly entire trunks of trees have been discovered. Near the Kom-Kom, a branch of the Kaga River, I have collected numerous specimens‡.

Section at Dordrecht. — In the section (fig. 8) the portions marked a, a, a are covered with debris. No. 1 protrudes in enormous masses of greenstone or basalt (" ironstone" of the colonists), which, judging from the line of exposure, must be conformable with the strata on which they seem to rest§. About 50 feet below, a rather compact sandstone is exposed, resting upon a claystone (No. 2)||, about two feet thick ; this, again, upon No. 3, a coarse-grained greyish sandstone¶, twelve or fourteen feet ; and immediately beneath this is No. 4, grey indurated shale. Below this is a coarse friable brownish sandstone (No. 5), resting on No. 6, which is very similar, but full of ferruginous patches and nodules, specimens of which are sent**. Many of these nodules are filled with ochres, fine im-


 * For the remainder of the papers read at this Meeting, see pp. 49-73.

† For Mr. Stow's description of a section of the Karoo beds of the Rhenosterberg, an offshoot of the Sneewbergen, see Quart. Journ. Geol. Soc. vol. xv. p. 194. — T. R. J.

‡ Several segments of probably coniferous trunks were sent by the author. — T. R. J.

§ The specimen of No. 1 sent is a small exfoliating nodule of greenstone. — T. R. J.

— T. R. J.
 * The specimen of No. 2 sent is a piece of felspathic trap (claystone).

¶ With felspathic cement. — T. R. J.

oxide, showing transverse lines of stratification externally, and containing ochre. — T. R. J.
 * " D. S. 2." Nodules of quartz grit, with some felspar, cemented with iron-