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The evidence is of the plainest possible character and is simply this: We find raised up on the flanks of these mountains, elevated by the forces of upheaval which have given rise to them, masses of Cretaceous rock which formed the bottom of the sea before those mountains existed.
During the Lower Cretaceous alone there were no less than six successive changes in the faunas which inhabited the limestone-making sea which then covered Texas. We shall disregard these changes for the most part in describing the life of the era, and shall confine our view to some of the most important advances made in the leading types. Stromatopora have disappeared.
By standing on a jutting ledge of the soft cretaceous rock, and holding on by another ledge, which appeared not unlikely to come down and crush you, one could peep into the hole and comfort oneself with the thought that one was nearer a kingfisher's nest than is usually vouchsafed to mortal man.
Being already tolerably familiar with the fossils of the Jura, it occurred to me to compare those of the upper and lower slope; and to my surprise I found that they were everywhere different, and that those of the lower slope were invariably Cretaceous in character, while those of the upper slope were Jurassic.
Besides the Belemnite there are other genera, such as Baculites and Hamites, never found in strata newer than the cretaceous, but frequently met with in these Maestricht beds. On the other hand, Voluta, Fasciolaria, and other genera of univalve shells, usually met with only in tertiary strata, occur. The upper part of the rock, about 20 feet thick, as seen in St.
This hardness may, with good reason, be ascribed to the salt of nitre, which contracts a certain viscidity from the rain wherewith it is mixed, and which easily penetrates into these stones, because their substance is spongy and cretaceous, and adheres to the tongue as hartshorn.
There is a difference in the form of the joints of the back-bone, and in some minor particulars, between the crocodiles of the present epoch and those which lived before the chalk; but in the cretaceous epoch, as I have already mentioned, the crocodiles had assumed the modern type of structure.
It is not till we arrive at the Cretaceous period that they begin to appear, sparingly at first, and only playing a conspicuous part, together with the palms and other endogens, in the Tertiary epoch.
The remarks given on the several foregoing shells, show that, in M. d'Orbigny's opinion, the Pecten, Ostrea, Turritella, and Hippurite indicate the cretaceous period; and the Gryphaea appears to Professor Forbes to be identical with a species, associated in Southern India with unquestionably cretaceous forms.
Dr. Geologists have long been familiar with the fact that on the northern coast of Sicily, between Termini on the east, and Trapani on the west, there are several caves containing the bones of extinct animals. These caves are situated in rocks of Hippurite limestone, a member of the Cretaceous series, and some of them may be seen on both sides of the Bay of Palermo.
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