But while, in this particular case, the size of the comet, or its more fiery nature, melted the surface of the globe, and changed the very texture of the solid rocks, we find in the geological record the evidences of repeated visitations when Drift was thrown upon the earth in great quantities; but the heat, as in the last Drift Age, was not great enough to consume all things. In the Cambrian formation, conglomerates are found, combinations of stones and hardened clay, very much like the true "till." In the Lower Silurian of the south of Scotland, large blocks and bowlders (from one foot to five feet in diameter) [1. Dana's "Text-Book," p. 156.] {p. 434} are found, "of gneiss, syenite, granite, etc., none of which belong to the rocks of that neighborhood." Geikie says: "Possibly these bowlders may have come from some ancient Atlantis, transported by ice."[1] The conglomerates belonging to the Old Red Sandstone formation in the north of England and in Scotland, we are told, "closely resemble a consolidated bowlder drift."[2] Near Victoria, in Australia, a conglomerate was found _nearly one hundred feet in thickness_. "Great beds of conglomerate occur at the bottom of the Carboniferous, in various parts of Scotland, which it is difficult to believe are other than ancient morainic _débris_. They are frequently quite unstratified, and the stones _often show that peculiar blunted form which is so characteristic of glacial work_."[3] Professor Ramsay found well-scratched and blunted stones in a Permian conglomerate. In the north of Scotland, a coarse, bowlder-conglomerate is associated with the Jurassic strata. The Cretaceous formation has yielded great stones and bowlders. In the Eocene of Switzerland, erratics have been found, some angular and some rounded. They often attain great size; one measured one hundred and five feet in length, ninety feet in breadth, and forty-five feet in height. Some of the blocks consist of _a kind of granite not known to occur anywhere in the Alps_. Geikie says: "The occurrence in the Eocene of huge ice-carried blocks seems _incomprehensible_ when the general character of the Eocene fossils is taken into account, for these have a somewhat _tropical_ aspect. So, likewise, the appearance of ice-transported blocks in the Miocene is a _sore puzzle_, [1. "The Great Ice Age," p. 478. 2. Ibid., p. 479. 3. Ibid.] {p. 435} as the fossils imbedded in this formation speak to us of tropical and sub-tropical climates having prevailed in Central Europe."[1] It was precisely during the age when a warm climate prevailed in Spitzbergen and North Greenland that these erratics were dropped down on the plains of Italy! And, strange to say, just as we have found the Drift-deposits of Europe and America unfossiliferous,--that is to say, containing no traces of animal or vegetable life,--so these strange stone and clay deposits of other and more ancient ages were in like manner unfossiliferous.[2]