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Do the facts sustain this assumption? The little animals whose remains compose the great chalk-beds are alive and working. Inarticulate or molluscan life is seen in a sub-fossil condition in the Post Pliocene clays of Canada. They are just as they were in the beginning of their history. Species seem to be immutably fixed.
The chalk-beds are the highest which extend over a considerable space; but in hollows of these beds, comparatively limited in extent, there have been formed series of strata clays, limestones, marls, alternating to which the name of the Tertiary Formation has been applied.
In fact, one of the most characteristic traces of the southern sea which then stretched from England to Africa in the south and India in the east indicates a warm climate. It will be remembered that the Cretaceous ocean over Southern Europe had swarmed with the animalcules whose dead skeletons largely compose our chalk-beds.
It is believed that chalk-beds still forming in some of our present seas may form one continuous mass dating back to earliest geologic ages. On the other hand, rocks different in character maybe formed at the same time in regions not far apart say a sandstone along shore, a coral limestone farther seaward, and a chalk-bed beyond.
The microscope and other means of scientific observation assure us that the chalk-beds of England and of France, the coral reefs of marine waters in warm climates, vast calcareous and silicious deposits in the sea and in many fresh-water ponds, the common polishing earths and slates, and many species of apparently dense and solid rock, are the work of the humble organisms of which I speak, often, indeed, of animaculae so small as to become visible only by the aid of lenses magnifying thousands of times the linear measures.
In those dim geologic epochs, where annals are written on Mica Slate, Clay Slate, and Silurian Systems, on Old Red Sandstones and New, on Primary and Secondary Rocks and Tertiary Chalk-beds, there were topsy-turvyings amongst the hills and gambollings and skippings of mountains, to which the piling of Pelion upon Ossa was a mere cobblestone feat. Alps and Apennines then played at leap-frog.
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