Page:Mannering - With axe and rope in the New Zealand Alps.djvu/22

4 the lower parts of the valleys, the heads of which they now occupy; whilst the formation of nearly all the lakes in the South Island can be traced to the action of ice and the deposition of terminal moraines, prior to a period of retreat of the ice.

There is an interesting feature in the glaciers of this country peculiar to them; I refer to the deposition of singularly extensive moraines. The lower parts of the large glaciers on the eastern slopes are, in nearly every instance, completely covered with accumulated débris derived from the moraines. This is variously accounted for by the antiquity of the mountain chain, the slow rate of motion in the ice, and great denudation from rocks which are much jointed and offer but little resistance to the splitting powers of freezing infiltrated water.

The western glaciers I am not personally acquainted with, but I understand that they do not carry anything like the amount of moraine, and I imagine the cause of the disparity will be found in a faster motion of the ice, and (a yet more potent factor) in the dip of the strata of the rocks, which is from east to west, the broken faces being eastward and the slab-like faces westward.