On the Palæozoic Rocks and Fossils of the State of New York. Part II. The Stratigraphy and Classification of the Series

Abstract

Abstract In the synoptical view of the strata and fossils of the palæozoic basin of New York, read before the Society Nov. 18, 1857, the author desired to arrange the vast stores of information contained in the Official Reports of the State Geologists of New York in a methodical and accessible form; and in this Second Part of the Memoir he treated succinctly of the stratigraphical arrangements hitherto used, and the classification now adopted by himself. This is but little modified from that proposed by De Verneuil; and is mainly characterized by the union of certain sections of the series into natural groups, and by the establishment of a distinct middle Silurian stage, and an equally distinct middle Devonian stage. The lithological and palmontological characters of the several groups of strata were then treated of in succession; their resemblances and differences, in these respects, being carefully noted. From the consideration of the stratigraphical details contained in this and the preceding paper, Dr. Bigsby deduces two main conclusions; namely, 1. That, from the Potsdam sandstone to the summit of the Carboniferous rocks, these strata were laid down in comparative quiet ; subject to occasional, vertical, variable, secular oscillations, which led to considerable superficial changes. 2. That their elevation, foldings, fractures, and metamorphism were effected after the deposition of the whole; in a single prolonged transaction, and principally in a N.E. and N.W. direction, along the present Appalachian ridges and their continuation from Labrador to near the Gulf of Mexico. The evidences on which these two propositions rest were next detailed; and the views of the Professors Rogers on these points, and the author's objections, were stated in full.