IT is a fact well known to geologists that the drifts laid down in the peripheral portions of the area affected by the Quaternary Glaciation differ markedly from those developed nearer in to the glacial centres. Beyond, perhaps, a vague suggestion that this may have been due to different climatic conditions during the successive stages of the retreat, no adequate or even partial explanation of the phenomenon has ever been brought forward. Pursuing a line of thought suggested by Dr. Matti Sauramo, in his paper on the glacial retreat in Southern Finland, it now seems possible to offer an explanation based merely on the simple assumption of a greater degree of cold during the maximum of glaciation than obtained during the later stages of the retreat.