THE PALEOLITHIC PERIOD IN NORTH AMERICA.
Most archreologists and geologists who have personally examined the evidence are now of accord in the opinion that man existed in various parts of North America during the Glacial Epoch, and a few insist that be was there long anterior to that event. The testimony on which this conclusion is based and the character of human remains discovered may be presented under the names of the various localities believed to contain these ancient objects.
Trenton southern border of the great ice-sheet, push ing before it its terminal moraines, descended on the Atlantic coast to the latitude of New York harbor. From that point it extended north west and west, crossing the Delaware River a few miles above its junc tion with the Lehigh. As the ice melted, furious torrents poured down the valley of the Delaware, carrying with them sand and stones, which first found a spot where they could sink to the bottom and be at rest in the broad expanse, south of the hills, where the city of Trenton now stands. Here the debris was deposited in strata sometimes forty, and even fifty, feet in thickness, resting upon a secondary clay formation.
Scattered through this early postglacial gravel deposit, at various depths down to the very bottom, and sometimes on the clay itself, are found stone implements (pl. 1, figs. 15-18) fashioned by the hand of man.
The first to make this remarkable discovery was Dr. Charles C. Abbott of Trenton, who reported it in 1877. Since then the Trenton gravels have been carefully studied by a number of eminent scientists, such as Professor W. Boyd Dawkins of England and Professor Henry W. Haynes of Boston, both high authorities upon palreolithic implements, and they agree in pronouncing that the implements found by Dr. Abbott, both in their forms and in the situations in which they occur, closely correspond to those which are disinterred from the river drift and gravel-beds of the Thames and the Somme.
A study of the locality at once brings these implements into definite relations to the Glacial Period. One of the most able glacialists in the
United States, Professor G. Frederick Wright, states positively that " the gravel in which they are found is glacial gravel deposited on the banks of the Delaware when, during the last stages of the Glacial Period, the river was swollen with vast floods of water from the melting ice. Man was on this continent at that period, when the climate and ice of Green land extended to the mouth of New York harbor." Professor H. Cargill Lewis, who has also devoted much care to the study of glacial action in the United States, and has issued a special report on the age of the Tren ton gravels, agrees with this, pronouncing the gravels "a postglacial deposit, but still a phenomenon of essentially glacial times." We may conclude without hesitation, therefore, that in these antique tools we have decisive evidence of the presence of man on the banks of the Delaware River for the whole period during which were deposited the fifty feet or more of gravel.
The gravels of which we have been speaking are overlaid by a bed of sand from one to five feet in thickness, deposited at a later date, of course, and under other conditions. In this sand arc found rudely-chipped arrow-heads, less symmetrical than those which appear in abundance in the surface loam resting upon the sand and inferior to them in workmanship. Moreover, the material differs. The implements both of the gravel and the sand are of argillite, a tenacious stone abounding in the vicinity; while the surface finds, extremely well made, are of flint, quartzite, and jasper, often of such lithological characters that they indicate an origin at some distant point.
Thus we have in the Trenton deposits the best illustration yet pointed out on the continent of the succession of the older Paleolithic Period, that of simple implements; the newer Paleolithic Period, that of com pound implements,—both of stone merely chipped; and, lastly, the Neo lithic Period, with its weapons and utensils of bored, ground, and polished stone.