. The geography of New Zealand. Historical, physical, political, and commercial . ged bush scenery on its visitors stay at Pipiriki, which is becoming animportant settlement. Chapter VIL—GLACIERS. Formation.—The snow that falls on the higherslopes of mountain ridges is not melted in thesummer months. By pressure and partial meltingit become.^ compacted into solid ice. This behavesas an extremely thick or viscous fluid, and graduallyflows down into the valleys. A glacier flows morerapidly in the middle than at the sides and morerapidly at the bottom than at the top. Its flow iscontinu
. The geography of New Zealand. Historical, physical, political, and commercial . ged bush scenery on its visitors stay at Pipiriki, which is becoming animportant settlement. Chapter VIL—GLACIERS. Formation.—The snow that falls on the higherslopes of mountain ridges is not melted in thesummer months. By pressure and partial meltingit become.^ compacted into solid ice. This behavesas an extremely thick or viscous fluid, and graduallyflows down into the valleys. A glacier flows morerapidly in the middle than at the sides and morerapidly at the bottom than at the top. Its flow iscontinued along the valleys until it reaches a level 170 GEOGRAPHY OF NEW ZEALAND where the rate of melting is more rapid than therate of supply of ice. At this level the glacier, asthe ice stream is called, is replaced by a riverwhich is formed of the water supplied by themelting ice. On the more precipitous slopes of the mountainsthe flow of ice to the valleys is not gradual. Fromtime to time the weight of masses of ice causes themto break away from the portion behind, and they. Heaps of glacial ii ,i,iii<r jii I ti.^iiiaii valley. Mount Cookin background. fall as huge avalanches or ice slips into the avalanches carry with them rocks and stonesthat they tear from the mountain sides. Theseaccumulate on the sides of the glacier, and formlateral moraines, which are carried on the surfaceof the ice as it slowly marches on. Where a side valley joins the main one, the twolateral moraines unite and form a medial moraine, GLACIERS 171 which may extend as a line of rock fragments downthe centre of the srlacier. In the upper portions of aglacier more snow falls every year than melts, sothe moraines are covered with congealed snow orice, and the unsullied ice surface extends from sideto side of the glacier valley. Functions.—In the lower portion of the glaciercourse, where the surface melts more rapidly thanit is replaced by fresh snow, all the moraine frag-ments become vis
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