V.—The Eozoic Rocks of North America

Extract

The following is an abstract of Dr. Hunt's paper. According to the author there is found among the pre-Cambrian strata of North America an invariable succession of crystalline stratified rocks, which have been by him divided into several great groups, the constituents of which become progressively less massive and less crystalline until we reach the sediments of Palæsozoic time; of which the Cambrian is regarded as the basal member. Since all of these pre-Cambrian rocks, with the exception, perhaps, of the lowest or fundamental gneiss, present evidences, direct or indirect, of the existence of organic life at the time of their deposition, it seems proper to include them under the general title of Eozoic, proposed by Sir J. W. Dawson. That of Archæsan, employed by some geologists to designate these pre-Cambrian rocks, appears too indefinite in its signification, and, moreover, is not in accordance with the nomenclature generally adopted for the great divisions succeeding. These Eozoic rocks include both the Primitive and the Transition divisions of Werner.