into which the glaciers of the high valleys flowed and calved their icebergs--these latter scattering erratics and earthy débris over the drowned areas. Sartorius von Waltershausen[AB] set forth this view in an elaborate and well-illustrated paper. Unfortunately for his hypothesis no trace of the supposed great lakes or the inland sea has ever been detected: on the contrary, the character of the morainic accumulations, and the symmetrical grouping and radiation of the erratics and perched blocks over the foot-hills and low-grounds, show that these last have been invaded and overflowed by the glaciers themselves. Even the most strenuous upholders of the efficacy of icebergs as originators of some boulder-clays, admit that the boulder-clay or till, of what we may call the inner or central region of a glaciated tract is the product of land-ice. Under this category comes the boulder-clay of Norway, Sweden, and Finland, and of the Alpine Lands of central Europe, not to speak of the hilly parts of our own islands. [AB] "Untersuchungen über die Klimate der Gegenwart und der Vorwelt," etc.--_Natuurkundige Verhandelingen v. d. Holland. Maatsch. d. Wetensch. te Haarlem_, 1865. When we come to study the drifts of the peripheral areas, it is not difficult to see why these should be considered to have had a different origin. They present certain features which, although not absent from the glacial deposits of the inner region, are not nearly so characteristic of such upland tracts. I refer especially to the frequent interstratification of boulder-clays with well-bedded deposits of clay, sand, and gravel; and to the fact that these boulder-clays are often less compressed than those of the inner region, and have even occasionally a silt-like character. Such appearances do seem at first to be readily explained on the assumption that the deposits have been accumulated in water opposite the margin of a continental glacier or ice-sheet--and this was the view which several able investigators in Germany were for some time inclined to adopt.