The same line of reasoning is conclusive respecting the innumerable boulders which cover the northern portion of Ohio, where I have my residence. The whole State of Ohio, and indeed almost the entire Mississippi basin between the Appalachian and the Rocky Mountains, is completely covered, and to a great depth, with stratified rocks which have been but slightly disturbed in the elevation of the continent; yet, down to an irregular border-line running east and west, granitic boulders everywhere occur in great numbers. In the locality spoken of in northern Ohio the elevation of the country is from two hundred to five hundred feet above the level of Lake Erie. The nearest outcrops of granitic rock occur about four hundred miles to the north, in Canada. After the meeting of the American Association for the Advancement of Science in Toronto in the summer of 1889, I had the privilege of joining a company of geologists in an excursion, conducted by members of the Canadian Survey, to visit the region beyond Lake Nipissing, north of Lake Huron, where the ancient Laurentian and Huronian rocks are most typically developed. I took advantage of the trip to collect specimens of a great variety of the granites and gneisses and metamorphic schists and trap-rock of the region. On bringing them home I turned them over to the professor of geology, who at once set his class at work to see if they could match my fragments from Canada with corresponding fragments from the boulders of the vicinity. To the great gratification, both of the pupils and myself, they were able to do so in almost every case; and so they might have done in any county or township to the south until reaching the limit of glacier action which I had previously mapped. Here, at Oberlin, on the north side of the water-shed, it is possible to imagine that we are on the southern border of an ancient lake upon whose bosom floating ice had brought these objects from their distant home in Canada. But this theory would not apply to the portion of the State which is south of the water-shed and which slopes rapidly towards the Gulf of Mexico. Yet the distribution of boulders is practically uniform over the glaciated area on both sides of the water-shed, constituting thus an indisputable proof of the glacial theory. 4th. As the significance of the gravel terraces which mark the lines of outward drainage from the glaciated area cannot well be indicated in a single paragraph, the reader is referred for further information upon this point to the general statements respecting them throughout the next chapter. CHAPTER V. ANCIENT GLACIERS IN THE WESTERN HEMISPHERE. _New England._