Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/702

 hollows above described, is free. Above the bed of nodules rises an abrupt precipice (about 40 feet high) of grey sandstone, of rather a fine texture. Above this a dun-coloured shale (16), 140 or 150 feet thick, slopes upwards to No. 17, which is a band of fine yellow clay about a foot thick. From this another precipitous face of about 40 feet (No. 18) of very fine-grained sandstone rises, and above this is a light- coloured shale nearly 200 feet thick. No. 20 is another fine-grained sandstone. The unexplored rocks above this rise some 500 feet, in three successive tiers, as shown in the section. The precipitous portions are sandstones ; and it is highly probable that the intervening spaces are occupied by shales. Near the foot of the mountain (at a) a dyke makes its appearance, but, as in the other instances mentioned, without causing any change either in the position or character of the rock through which it passes. The rocks here described add another 1000 feet to those before mentioned.

The circumstance that makes this section of the Klaas-Smit's River of great interest is that here are found the first indications of connecting links of the strata north and south of the Stormberg range ; and thus the equivalents of 4, 5, 6, and 7, near the bottom of that part of the mountain now under examination, are to be found almost at the top of the Hangklip (which is the culminating point of some mountains nearly sixteen miles further south) immediately under the precipice, at a height of 6500 feet above the level of the sea. Further, the yellow clay at " 17," the gritty, noduliferous, and ferruginous sandstone " 13," and bluish-brown clay " 12," remind us of the very similar deposits found at Dordrecht (Section, fig. 8), described at page 523 ; and it is to be hoped that before long other sections may be obtained that will throw still further light upon this interesting subject.

Part III. — The Climatal changes of South Africa (Eastern Province AND THE VICINITY), AS INDICATED BY ITS GEOLOGY AND Fossils ; and especially the Glacial Denudation of the Karoo Strata.

The consideration of the climatal changes that have taken place in this portion of the ancient world during the deposition of the various formations treated of in the first part of this memoir will lead me to make some remarks upon the probable cause of the denudation of a large portion of the Dicynodon-rocks in the Eastern Province.

Tertiary Climates. — The evidence of the Pliocene shells of the superficial limestone of the Zwartkops heights and elsewhere leads us to believe that the climate of South Africa must have been of a far more tropical character than at present. Take, for instance, the characteristic Venericardia of that limestone : this has migrated along the coast some 29 or 30 degrees, and is now found within a few degrees of the equator, near Zanzibar, gradually driven, as I presume it must have been, further and further north by a