Murchison naturally made the most of the fossils collected, and was soon able to show that the transition series could be recognized by them, just as younger formations had fossils peculiar to themselves; as he zealously worked on he followed the fossiliferous rocks further afield and continually lower in the series.
They are overlain by the fossiliferous limestones of the Antalo group. Around Chelga and Adigrat coal-bearing beds occur, which Blanford suggests may be of the same age as the coalbearing strata of India.
The deposits of most commercial importance are the limonites and brown hematites found west of the Cumberland Plateau, and the fossiliferous red hematite which crops out along the eastern base of that plateau.
The Lower Cretaceous consists chiefly of sandstones and shales and the Middle Cretaceous of very fossiliferous limestone.
It is marked by grey clays and sands, lignitic fossiliferous clays, beds of lignite or brown coal, sometimes 8 ft.
The northern zone is the Tibetan, in which fossiliferous beds of Palaeozoic and Mesozoic age are largely developed - excepting in the north-west no such rocks are known on the southern flanks.
In the peninsula, however, no marine fossils have yet been found of earlier date than J urassic and Cretaceous, and these are confined to the neighbourhood of the coasts; the principal fossiliferous deposits are the plantbearing beds of the Gondwana series, and there can he no doubt that, at least since the Carboniferous period, nearly the whole of the Peninsula has been land.
The depths of the Black Sea are lifeless, higher organic life not being known to exist below loo fathoms. Fossiliferous remains of Dreissena, Cardium and other molluscs have, however, been dredged up, which help to show that conditions formerly existed in the Black Sea similar to those that exist at the present day in the Caspian Sea.
These fossiliferous strata are developed in greatest thickness in the north-west peninsula.
The erosion of the region must have been far advanced, perhaps practically completed, in very ancient times, for the even surface of the peneplain is overlapped by fossiliferous marine strata of early geological date (Cambrian); and this shows that a depression of the region beneath an ancient sea took place after a long existence as dry land.