From Greenland comes abundant evidence of a post-glacial warm period coincident with a subsidence of about 80 feet. Raised beaches all along the west coast contain mollusca, some species of which are not now living north of the St. Lawrence estuary. On the other hand, some northern species which lived off the west coast during the glacial maximum retreated northwards during this period, and have not re-established themselves, though the climate is now suitable. Further, K. Steenstrup describes the occurrence of “dead ice” at several places in North Greenland—masses of ice which have become separated from their parent glaciers owing to rapid recession, and are now buried in morainic matter. Subsequently the ice again advanced, and in some cases a new glacier has advanced over these masses of “dead ice.” Passing to the mainland of North America, we find in eastern Canada colonies of southern mollusca, especially oysters and quohogs, separated from their main area of distribution south of Cape Cod by a wide area of cold seas—the Gulf of Maine and Bay of Fundy. At the beginning of the warm phase the land lay slightly below its present level, but subsequently rose above it. The climate became still warmer, until its temperature resembled that of the middle New England States. At the same time the rainfall diminished and the peat-bogs were replaced by forests of hardwood trees. In the basin of the Great Lakes the warm period is represented by gravel beds in the Niagara gorge, which from their position must, according to the most recent determinations, have been formed about 4000 to 3000 B.C. These gravels contain shells of fresh-water mollusca, especially species of _Unio_, which are not now living in the St. Lawrence system, but are found in tributaries of the Mississippi further south. Further south on the eastern coast of the United States there are marine deposits indicating a slight submergence, with a climate somewhat warmer than the present. Passing to South America, we find in southern Patagonia and Tierra del Fuego exactly similar evidence of a post-glacial subsidence with a warmer climate than the present. Raised beaches at a height of 50 feet contain mollusca, some of which are now rare or extinct in that locality, and in sheltered situations plants are found still living whose nearest neighbours are some way to the north.