Triassic Fishes and Plants

Abstract

THE fourteenth of the splendid series of monographs issued, and so liberally distributed, by the U.S Geological Survey, is by Prof. Newberry, and deals with the fossil fishes and plants of the east coast Triassic areas known as the Palisades and the Connecticut Valley. Their red shales, sandstones, and conglomerates occur for the most part in narrow basins parallel to the coast or coast ranges, intersected by sheets and dykes of diabase, and average about 5000 feet in thickness. In a very few spots the almost barren shales are charged with carbonaceous matter, and in these plant and fish remains have been met with. The two areas are separated by the wide Hudson Valley tract of older rocks, and are distinguished by all the Palisade beds dipping at an angle of 3° to 15° west, while the Connecticut beds dip as uniformly to the east. Various theories accounting for their deposition are discussed, but the simplest would be to regard them as local deposits of a flat, shallow, sandy, thoroughly sheltered coast-line, subjected to heavy tides. With gradual and intermittent subsidence, and consequent continued encroachment on the land, most extensive beds of varying fineness might be formed. A dip, such as that observed, would ensue, as the beds passed successively under low-water mark, and fell under pressure of the sea into the ordinary slopes of a shelving shore. Sun cracks, ripple marks, and footprints would be formed in each bed in the belt exposed between the high-water marks of neap and spring tides. That the deposits originally swarmed with prey is evident from the footprints of nearly 100 varieties of animals, only a part of which were perhaps amphibious, which made them their promenade. Almost every trace, however, of such organisms as mollusca, annelids, Crustacea, and plants, have disappeared.

Fossil Fishes and Fossil Plants of the Triassic Rocks of New Jersey and the Connecticut Valley.

By J. S. Newberry. (Washington: Government Printing Office, 1888.)