Page:Popular Science Monthly Volume 13.djvu/665

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GEOLOGICAL HISTORY OF NEW YORK.

that a depressed area once existed between the New York ridge and the New Jersey highlands, and that this trough was an estuary swept by the tides, much like the Bay of Fundy. Here, as there, the shallows and mud-flats exposed by the ebb were places of resort for many of the animals inhabiting the district; but there is this difference, that in the lapse of time the fauna of the country has completely changed, and the fishes which inhabited the waters of the Triassic estuary, as well as the reptilian monsters that perambulated its shores, have now utterly disappeared from the face of the earth.

The fishes of the Trias, being found at various localities both in New Jersey and the Connecticut Valley, early attracted attention, and many of them were described by Mr. W. C. Redfield—for many years a leading scientist of New York. More recently large collections of them have been made by the writer, so that now they are pretty well known. They form some twenty species of four genera—all ganoids—related to the Lepidosteus and Amia of our interior lakes and rivers.

Of the molluscous life of the age in this region we, know almost nothing, since the marine deposits which contain its remains are not now above the ocean-level, and the fresh-water and estuary beds exposed to our observation have yet yielded none. Of the land-animals scarcely any traces have been found except their footprints. These prove that a motley crowd of reptiles and amphibians, some of huge size, and, according to our notions, of uncouth and hideous shapes, thronged the shores of our Triassic bay in such numbers, so swift and so well armed for attack and defense, that this must have been anything but a congenial place of residence for a peaceably-disposed citizen.

The hills which overlooked the Triassic lagoons—as they now do their exposed beds, the plains of New Jersey—were covered with forests of Araucarian pines, and the lowlands with thickets of sago palms and ferns, while gigantic scouring rushes lined the marshy shores. There were no oaks, maples, nor walnuts in the forests, and probably no flower-bearing shrubs or herbs in the undergrowth, for nearly all the fruits and flowers belong to the angiosperms and palms, neither of which had yet made their appearance on the earth's surface. Hence, the vegetation must have been sombre and uninteresting, compared with that of the present day, and, as there were no grasses in it, ill-adapted to the wants of man or the higher animals.

At the close of the Triassic age this region became the scene of great and destructive physical changes, which must have completely altered its aspect. Along the Triassic belt, both east and west, subsidences took place, or displacements by lateral pressure which tilted up all the strata until they stood at an angle with the horizon of 15°, where they still remain—those on the east dipping eastward, those of New Jersey toward the west. At the same time deep fractures reached the source of molten matter below, and this was forced up, either in dikes through vertical fissures, or in sheets between the beds of the