Another deposit of gravel further down the Delaware River is much older: The best authorities in such matters believe that it was deposited, not after the recession of the great glacier which once covered Canada and the northern portion of the United States, but while that tremendous phenomena was at its height, and when all the streams of the central United States were periodically choked with vast masses of ice and snow. In this, which is called the Columbian gravel, chipped stone implements have been found by Mr. Cresson, all of the “simple” variety, and at such depths as to preclude the theory of an intrusive deposit. These discoveries carry the age of the appearance of man in the Delaware valley back to a date which is possibly over a hundred thousand years ago. The great glacier left its mass of boulders, pebbles and broken stone, which it pushed before it, or carried with it, in a long line of so-called “moraines,” extending, roughly speaking, from New York to St. Louis. In this mass, at its edges where the great wash from the melting ice poured down, palæoliths have been found in undisturbed position, proving that also there man had struggled with the inclemency of the ice-age, and, poorly provided as he was, had come out victorious. Here too all the implements he left are of the “simple” type, indicating at once the vast antiquity of the period and the presence of a race substantially the same as that to the east at the same date. No tribe has been known to history which was confined to the knowledge of “simple” implements, or which manufactured stone implements exclusively in the Palæolithic forms. Wherever, therefore, these are found without the admixture of artificially ground or polished stones we may be sure we face the remains of a time whose antiquity cannot be measured by any chronology applied to the historic records of humanity.