The Labradorean and Keewatin ice sheets everywhere coalesced except in two places. One of these is an area of about 10,000 square miles mostly in southwestern Wisconsin. In spite of several ice invasions during the Ice Age, this area, hundreds of miles north of the southern limit of the ice sheets, was never ice-covered. There is a total absence of records of glaciation within this area, and so we here have an excellent sample of the kind of topography which prevailed over the northern Mississippi Valley just before the advent of the ice. A much smaller, nonglaciated area occurs in northeastern Missouri near the southern limit of ice extension. The Cordilleran ice sheet was the smallest of the three, and it was probably not such a continuous mass of ice, the higher mountains projecting above its surface. A surprising fact is that neither this ice sheet nor any other overspread northern Alaska, which is well within the Arctic Circle, during the Ice Age. More than likely the temperature was low enough, but precipitation of snow was not sufficient to permit the building up of a great glacier. At the same time that nearly 4,000,000 square miles of North America were ice-covered, about 600,000 square miles of northern Europe were buried under ice which spread from the one great center over Scandinavia southwest, south, and southeast over most of the British Isles, well into Germany, and well into Russia. In both North America and Europe the high mountains, well south of the great glacier limits, especially the Sierras, Rockies, Alps, Pyrenees, and Caucasus, supported many large local glaciers in valleys which now contain none at all or only relatively small ones. Records of glaciation, such as glacial scratches, bowlders, lakes, etc., occur high up in the White and Green Mountains, Adirondacks, Catskills, and the Berkshire Hills, thus proving that the ice must have been at least some thousands of feet thick over New England and New York. We have good reason to believe that even the highest summits, except possibly in the Catskills, from 4,000 to over 6,000 feet above sea level, were completely submerged under the ice. On top of a mountain of Archeozoic granite nearly 4,000 feet in altitude, facing the St. Lawrence Valley in northern New York, the writer has found many fragments of sandstone which were picked off by the ice in the low valley, moved southward a good many miles, and uphill several thousand feet to the top of the mountain. The reader may wonder how a great glacier at least a mile thick in northern New York could have thinned out to disappearance within the short distance to the southern border of the State, but observations on existing large glaciers show that it is quite the habit for them to thin out very rapidly near their margins, thus producing steep ice fronts.