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Taking these facts in conjunction with the positive evidence of the existence, during the Cretaceous epoch, of a deep ocean where now lies the dry land of central and southern Europe, northern Africa, and western and southern Asia; and of the gradual diminution of this ocean during the older tertiary epoch, until it is represented at the present day by such teacupfuls as the Caspian, the Black Sea, and the Mediterranean; the supposition of Dr.
But every device if we may so regard these changes is useless, and the devastating agency of the Cretaceous, whatever it was, removes the Ammonites and Belemnites from the scene. The Mollusc world, like the world of plants and of reptiles, approaches its modern aspect. In the fish world, too, there is an effective selection in the course of the Cretaceous.
It will be remembered that, whereas the first of these European revolutions was a sharp and massive upheaval, the second consisted in a more scattered and irregular series of disturbances, spread over the fourth and fifth decades of the nineteenth century; but they amounted, in effect, to a revolution. So it is with the Cretaceous Revolution.
There are families of fishes whose type of construction has persisted all the way from the carboniferous rock right up to the cretaceous; and others which have lasted through almost the whole range of the secondary rocks, and from the lias to the older tertiaries.
There is little evidence of volcanic action throughout the long lapse of time extending backwards from the Cretaceous to the Triassic epochs, that is to say, throughout the Mesozoic or Secondary period, and it is not till we reach the Palæozoic strata that evidence of volcanic action unmistakably presents itself. Permian Period.
That it was an extinct mammal of the whale tribe has since been placed beyond all doubt by discovery of the entire skull of another fossil species of the same family, having the double occipital condyles only met with in mammals, and the convoluted tympanic bones which are characteristic of cetaceans. Lapse of Time between Cretaceous and Eocene Periods. Maestricht Beds.
This leads to the supposition that there may have been, in that age, a series of river- receiving estuaries along the border of some such great ocean as the Atlantic, of which that of modern Sussex is only an example. The record of this period consists of a series of strata, in which chalk beds make a conspicuous appearance, and which is therefore called the cretaceous system or formation.
The geologic clock ticked out its centuries until the swamps of the Coal Period were full of Peter's Oldest Inhabitants in the form of Dinosaurs and then came the Cretaceous Period and the Great Architect looked down and bade the Rockies arise, and tooled them into beauty with His blue-green glaciers and His singing rivers, and touched the lordliest peaks with wine-glow and filled the azure valleys with music and peace.
The British volcanic eruptions now under consideration are all later than the Cretaceous period.
Nevertheless, we may expect the discovery in England, and still more when we extend our survey to the Continent, of beds of passage intermediate between the Upper and Lower Cretaceous.
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