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PROFESSOR T. G. BONNEY ON A COLLECTION OF 
carboniferous. In Sinai, as in Socotra, we have huge masses of limestone, which in 
like way form great plateaux—as, for example, the Tih—and were deposited in an 
ocean, in which the well-known peaks of Sinai probably formed rocky islands, but 
deposition there commenced at an earlier period than we can venture with the evidence 
at present before us to claim for Socotra, for the limestones of Sinai are assigned to part 
of the cretaceous and to the eocene age ; the Nummulitic limestone, for example, being 
finely developed as in Wady Dhaghadeh. Coraliferous beds of miocene age are, however, 
found in that region.* The rocks of Sinai are cut by dykes of “ basalt, greenstone, and 
porphyrite,” the first of which, as in Socotra, are probably comparatively modern, but 
we do not find there, so far as I can learn, representatives of the great group of the 
quartz-felsites and rhyolites which seem so enormously developed in Socotra and were 
certainly connected with active volcanos. The geological age of these cannot be 
determined. They are undoubtedly older than the limestone group; so that, if no 
part of this is earlier than the middle tertiary, they might belong to any geological 
period between that and the latest Precambrian, to the volcanic rocks of which they 
have, indeed, considerable resemblance. I am not aware that the “ argillite ” of 
Socotra—of which I can only say that it is older than the limestone—is represented 
in Sinai. As here, so also in Socotra, there are basalts of comparatively late geologic 
age—post miocene—and in the latter some compact trachytic rocks, which, however, 
differ from the older rhyolites, and are generally paler in colour. 
We have, then, in Socotra, as it seems to me, evidence of rocks of an immense, and 
a land surface of a very great, antiquity. Excepting this argillite of uncertain age 
and limited extent, and perhaps some sandstone (also local), there is no evidence in 
the specimens before me to show that this island was submerged during any part of 
the palaeozoic or mesozoic period.! During the kainozoic it undoubtedly shared in the 
downward movement which affected so large a portion of the globe in and about the 
North African and mid-Asiatic districts; but I should infer that the invasion of the 
sea commenced much earlier in the Sinaitic peninsula, and think it possible that the 
topmost peaks of the Haggier Mountains were at no time wholly submerged. As it 
again rose from the waves—perhaps being for a while connected with the African 
continent—the meteoric forces resumed their work of sculpture and the waves began 
their work of insulation. Since then the fauna and flora have undergone their own 
modifications, but in the Haggier Hills we have probably a fragment of a continental 
* Bauerman, Quart Jour. Geol. Soc., vol. xxv., p. 37. 
t “Africa south of the Sahara was probably a stable area during many of the alterations of the relative 
levels of land and sea of the north and of Europe.”—Professor P. M. Duncan, Presidential Address to 
Geol. Soc. 1877, Journal, vol. xxxiii., p. 86 (Proceedings). West of the Sinai Peninsula old schists and 
granite crop out in Egypt, and east of it on the opposite side of the Gulf of Akabah, flanked in both 
cases by “Nubian sandstone.” See the map attached to the Presidential Address to the Geologists’ 
Association (delivei’ed November 3, 1882), by Mr. W. H. Hudleston (Proceedings, vol. viii., p. 1), in 
which is given an admirable summary of the Geology of Palestine and the neighbouring districts. 
