Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/679

 The strata of the Government Saltpan seem to follow, with (according to Dr. Atherstone) Trigonia, Turritella, Ostrea, and Cidaris pustulifera. At the Bethelsdorp pan C. pustulifera is found in the greatest abundance ; and spines and plates of the same Cidaris, found scattered on the sides of the outlier at the Salt Vlei, near Port Elizabeth, indicate the position of the associated clays on the opposite side of the Vlei (Section O, fig. 4), with their innumerable specimens of small Ostrea unmixed, as it seems at present, with the remains of Cidaris. As I have already said, so little is yet accurately known of the fossil contents of all these different strata that nothing can be done to decide the question of position with any degree of certainty until the fossils shall have been more fully studied and classified.

On looking at these collated sections (fig. 6) we at once see how much they differ from the apparent uniformity of the sandstones of the Zwartkops and Sundays Rivers (Sections A-G, fig. 3). These latter exhibit the features of an extended and uniform deposit, while the former display local differences of a very diversified character. Further, the more I have studied them the more I have been impressed with the idea that the position at present assigned to them * is not correct.

The following reasons may be given to explain this opinion. It is said that these strata are an earlier formation than those of the Zwartkops and Sundays Rivers series ; but has this been convincingly proved ? As far as I could obtain information, no good section has yet been pointed out (that is, anywhere between the quartzite hills of Port Elizabeth and the Grass-ridge) where these clays &c. are so situated as to demonstrate distinctly that they are really below, and the Zwartkops Trigonia-beds above. Even should we find them in a depression apparently lower, still this would prove nothing without a satisfactory junction in which the Trigonia-beds could be shown to be placed above the stratified clays ; whereas sections have been found the reverse of this. It might as well be argued that the red clay (g, g, in Section O, fig. 4) spread over the surface in different parts of the Oliphants-Hoek and Port-Elizabeth Divisions, instead of one of the most recent clays, is a very ancient one, because in the former locality it has been found (in sinking wells) to be upwards of 100 feet in depth, and in the latter, near the New Prison, about 70 feet — lower levels than either the sandstones or stratified clays have been found at. This clay has evidently been deposited in hollows, eroded out of the more ancient rocks ; and in the same way, I cannot help thinking, these " Saliferous Strata " have been deposited in positions where denudation had removed some of the earlier formations. This was especially the case where I examined the strata of the Government Saltpan ; for there these rods, as far as I could judge, when the dip of the Trigonia-sandstones is taken into consideration, must be placed above those of the Zwart-

formation. See Atherstone, loc. cit., and Quart. Journ. Geol. Soc. vol. xxiii. p. 149. — T. R. J.
 * That is, below the great Trigonia- and Ammonites-series of the Uitenhage