the human relics were found in deposits representing the closing episodes of the later epoch of Quaternary cold.
There are several cases in which traces of human activity have been reported from older deposits, but in which the discoveries are not so well authenticated. E. g., there is Dr. Koch's well-known record of the finding of mastodon remains in the Osage Valley, Missouri, associated with human implements and traces of fire, in deposits probably contemporaneous with those of the earlier ice-sheet; but the geologic relations have never been clearly made out, and the verity of the discovery has always been (perhaps unjustly) questioned. The finding of a fossilized human bone at Natchez, Mississippi, apparently associated with an early Quaternary fauna, is equally well known; but the attendant circumstances were not such as to carry conviction to the minds of contemporary students. Lewis, also, has described a paleolithic implement from aqueo-glacial gravels at Philadelphia; but he did not personally witness the discovery, and was not certain that the object came from the older (earliest glacial) and not the newer (latest glacial) gravels. It is significant that in all these cases the testimony is internally defective; and, since its acceptance would many times multiply human antiquity as established by collateral evidence (as clearly shown in Fig. 1), it would seem especially wise to reserve judgment upon it.
There are other cases in which human remains have been found in such position as to indicate great antiquity measured in years—e. g., the shell-heaps of Damariscotta River in Maine and St. John's River in Florida, representing a fauna now extinct or displaced; the enormous shell-heap at San Pablo on the Bay of San Francisco, which evidently represents a vast period of building; the shell-beds and superimposed deposits of the Aleutian Islands, which have been shown by Dall to represent at least three thousand years of accumulation, etc.; but in none of these cases is it possible to reduce the historic time-units to definite geologic time-units.
There are still other cases in which human relics have been reported from deposits of considerable geologic age—e. g., in Calaveras County, California, near Golden, Colorado, etc.; but, while the archæologic evidence would seem conclusive in at least one of these instances, it is impossible to confidently transmute the paleontologic record of the age of the deposits into the physical record which alone is sufficiently refined for the measure of human development; and it would thus seem wise to reserve judgment in these cases, also, with respect to the correlation of the deposits as well as to the association of the relics.
Excluding all doubtful cases, there remains a fairly consistent body of testimony indicating the existence of a widely distributed