The relative chronology of the European drift may be thus stated: first, and most modern, the superficial deposits of recent centuries with their mediæval traces of Frank and Gaul; and along with those, the tombs, the pottery, and other remains of the Roman period, scarcely perceptibly affected in their geological relations by nearly the whole interval of the Christian era; next, in the alluvium, seemingly embedded by natural accumulation at an average depth of fifteen feet, occur remains of a European Stone period, corresponding in many respects to those of the pfahlbauten, or pile villages of the Swiss Lakes; and, underlying such accumulations exceeding in their duration the whole historical period, we come at length to the tool-bearing drift, imbedding, along with the fossil remains of many extinct mammals, the implements of palæolithic man, fashioned seemingly when the rivers were only beginning the work of excavating the valleys which give their present contour to the landscapes of France and England. There, as elsewhere, we recognise progression from the most artless rudeness of tool manufacture, belonging to an epoch when the process of grinding flint or stone to an edge appears to have been unknown; through various stages of the primitive worker in stone, bone, ivory, and the like natural products; and then the discovery and gradual development of the metallurgic arts. Yet at the same time it must not be lost sight of that mere rudeness of workmanship is no evidence of antiquity. Nothing can well be conceived of more artless than some of the stone implements still in use among savage tribes of America. Moreover, it is to be noted that it is not amid the privations of an Arctic winter, with its analogies so suggestive of a condition of life corresponding to that of the men of Europe’s Palæolithic age, but in southern latitudes, with a climate which furnishes abundant resources for savage man, that the crudest efforts at tool-making now occur. In a report of the _United States Geological Survey_ for 1872, Professor Joseph Leidy furnishes an interesting account of numerous implements, rude as any in the Drift, observed by him while engaged on a survey at the base of the Unitah Mountains in Southern Wyoming. “In some places,” he remarks, “the stone implements are so numerous, and at the same time are so rudely constructed, that one is constantly in doubt when to consider them as natural or accidental, and when to view them as artificial.”[47] But with these, others are mingled of fine finish. The Shoshones who haunt the region seem to be incapable of such skill as the latter imply; and express the belief that they were a gift of the Great Spirit to their ancestors. Yet many are fresh in appearance; though others are worn and decomposed on the surface, and may, as Professor Leidy assumes, have lain there for centuries. The tendency is now, even among experienced archæologists, to assume that they are actually palæolithic. Mr. Thomas