Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/159

 terial as the underlying stratum. They consist of sandy marls and hard sandstones of a greyish-brown colour, with a few calcareous concretions. These rocks are partly covered at high water by the sea, which has hollowed out small cavities in them (Fig. 5). They have probably served at some period as a shelter for white people, as the natives of this district call them " Izinhluzabalungu," houses of the white men. These rocks only extend for a short distance, and only form isolated cliffs. They are found, too, at the Impengati river, and at some of the more southern rivulets which run into the sea between the boundary of Natal and the St. John's river(Umzimvooboo). The same are also recognized in the bed of a small stream, running into the St. Lucia bay, in the Zulu country. The strata forming these deposits are perfectly horizontal, and they rest upon a sandstone of much older age, which belongs to the very interesting series of the Karoo formation. It is remarkable that the Izinhluzabalungu rocks do not rest conformably upon the older formation, the plant- bearing sandstones.

Fig. 5. — Izinhluzabalungu Caves.

a. Karoo shales and sandstones, b. Sandstone with fossil wood &c. c. Trigonia-bed. d. Ammonite-bed. e. Gasteropoda-bed. f. Zone of Ammonites Gardeni.

I have been enabled to distinguish no fewer than five distinct faunas. The lowest stratum is a hard calcareous sandstone (6), very much worn by the sea breaking against it at high water. Large trees and branches are imbedded in it, lying about in all directions. The wood is traversed by large masses of Teredo, whose holes are filled with iron pyrites. Resting on this stratum is a bed of softer brown sandstone (c), with great abundance of Trigonioe. This bed is more exposed near the Umzambane river, and nearly concealed at the northern end of the deposits. It is overlain by sandstones and grits (d), containing Ammonites, resting upon which is a softer sandstone and grit (e), containing many fossils, mostly bivalves and Gasteropods. The roof of the caves is formed by a harder lime- stone stratum (f), which has not been so easily worn away by the sea as the underlying sandstone stratum. This limestone contains Ammonites Gardeni, Baily.