In exactly the same way the whole of the south-east of the island appears to have been covered uniformly with gently dipping beds of Tertiary sands and clays, beneath which the Cretaceous strata dipped.
The sea in which these strata were deposited seems to have attained its greatest extension in Upper Cretaceous times, when its waters spread over the whole of western Asia and even encroached slightly upon the Indian land.
Um, aged one and to a depth of 2500 fathoms. Fossil remains Dentalium, a half days; ventral are first found in the Silurian, but become most abundant from the Cretaceous onwards.
But more often worn to rolling downs; then the limestone range - writing-desk mountains that turn their steep fronts to the central snows; lastly low Cretaceous foothills, that sink softly into the steppe.
The high land in the west of the island and the somewhat less elevated region in the east are formed of Upper Tithonian and Lower Cretaceous limestones, the latter containing Rudistes.
The island is composed largely of crystalline and metamorphic rocks, but contains some cretaceous areas which hold extensive beds of coal, especially on the east coast.
Especially noteworthy was the discovery of birds with teeth both in Europe (Archaeopteryx) and in North America (Hesperornis), of Eocene stages in the history of the horse, and of the giant dinosauria of the Jurassic and Cretaceous in North America.
Except along the southern border of the Ardennes, and at one or two points in the middle of the Palaeozoic massif, Triassic and Jurassic beds are unknown in Belgium, and the Palaeozoic rocks are directly and unconformably overlaid by Cretaceous and Tertiary deposits.
Large deposits of phosphate occur in Russia, and those in the neighbourhood of Kertch have attracted some attention; it is said that the Cretaceous rocks between the rivers Dniester and Volga contain very large supplies of phosphate, though probably of low grade.
This form of stem, of a habit entirely different from that of recent Cycads and extinct Bennettites, points to the existence in the Mesozoic era of another type of Gymnosperm allied to the Bennettitales of the Jurassic and Cretaceous periods by its flowers, but possessing a distinctive character in its vegetative organs.