Naked Splintered Granite Crags

Otago Witness, Issue 1898, 19 June 1890, Page 36

Naked Splintered Granite Crags

rise up around the shores of Milford Sound to heights of over 6000 ft, while the bottom of the sound lies over 100 fathoms below the present waiter surface. The agency that chiselled out these wild We.st Coast gjrges, and cut down, often sharply, through 6000 ft or 7000 ft of solid granite was wonderfully potent ; but what could grind down a channel for itself so effectively as a licer of ice, whose under surface was btudded with hard gravel and shattered rock, and every square foot of which was forced downward with a pressure of hundreds, or, probably enough, thousands of tons ? Who that has noted the effect of sandpaper on moderately hard surfaces but must fully appreciate the effect of a glacier armed with a coated surface of hard rocky particles 1 We often find pieces of the hardest kinds of rock that have thus been carried forward, grinding and cutting against the rocky channel of some river of ice, till the under surface has become flat and smooth; and often the perpendicular or overhanging wall of some precipice shows a long scar made by such a stone as the ice in which it was embedded slowly carried it onvvard firm pressed against the rock} wall. The numerous gorges cut towards the sea, have consequently been slowly sinking, till some of them are submerged, and now constitute our far-famed sounds. The great depth of water in these sounds shows the amount of submergence since these gorges were sculptured out during the glacial period. Over the lake region, the glaciers, as they arrived at a lower attitude towards the close of the reign of ice at any rate, slowly melted and deposited their accumulated burdens of gravel, boulders, and rocky masses, thus forming moraines, as at Kingston. The origin of the lakes is due to these moraines blocking up the terminal portion of a gorge cut out by ice agency. The sounds and lakes are two of the most striking evidences of the g'acial period in this country ; but there are many minor features which bespeak the reign of ice in time past. .

There is an area of country in the basiu of the Taieri, through part of which the Otago Central railway passes, where glacial action in the past has been very active. It is probable enough here that the general surface of the country has been cut down hundreds, if not thousands, of feet. Trie landscape is dotted over with harder portions of mica-schist rock that must have resisted the erosive action of the glaciers, and were thus left like islets stranded in a sea of ice. The debris from this area is doubtless what constitutes a line of hills composed of boulder clay on the eastern side of Lake Waihola and flanking the Taieri Plain to Otakia. These are but a few of the plainer traces of the great ice age ; sapplemencary evidence is abundant.