THROUGH THE MOUNTAINS.

Dominion, Volume 1, Issue 242, 6 July 1908, Page 5

THROUGH THE MOUNTAINS.

GEOLOGY AT ARTHUR'S PASS.

In. the course of a paper on tho geological problems suggested by tho Arthurjs Pass tunnel, read before the Christchurch Philosophical Society last week, Mr. R. Speight, lecturer on geology at Canterbury College, said that tho Southern : Alps were of very old formation; that was shown by the fact that few earthquakes occurred in that locality, .which indicated that all tho strains were satisfied. Tho European. Alps and tho Himalayas were probably in the course of formation 1 , for movements wero at the present time going- on in those mountains. There was no. mountain range on tho faco of tho earth that was so high and had such low passes as tho Southern Alps, and that, was a proof of their ago. .Another feature -was that there'wore very few waterfalls. That, was-very largely because tho' rivers had been converting their falls into'rapids, no-ledges of rock remaining over which the rivers might run. Tho highest waterfall was tho Punch Bowl, which was ; 408 ft. high. A certain amount of heat was left in tho -Southern, Alps, as shown by the hot springs found thero, ,'and some of these springs might occur in. tho tunnel. The principal geological point of interest regarding the Arthur's Pass tunnel was that it would disclose the structure of tho range, chiefly by showing the character of tho rocks that would bo met with in the tunnel. Those rooks would bo. almost exclusively slates, a, hard kind ■ of sedimentary . rock, and'. a ipry hard sandstone. As far as a surface examination went thero wero no igiteous rocks to be found. Ho did not

think any gold was likely to bo found. Tho only mineral of cconomip importance likely to bo found thero was graphite. Another important feature of the range tho tunnel would disclose would bo tho sequence of rocks. That sequence was as a rulo worked out by a study of tho fossils, but, unfortunately, no fossils had been found between Mount Forlesse and tha West Coast. It'might also lie possible to get some idea of tho thickness of tho sedimentary rooks which formed tho great bulk of tho Southorn Alps.

The tunnel would also disclose the actual direction in which the folds of the mountains ran, and it might then be possible to tell in what direction came the great lateral thrust which formed tho ranges. The valleys in tho Bealeyend were probably formed by glacier action, but tho Otira Valley had been formed almost entirely .by He thought the origin of tho pass, was tho most interesting geological problem that required investigation. It was a great notch in the mountain range, and he believed that it had been formed by a dislocation in the drainage, owing to glacier , action. ■ The pass was the old bed of a glacier, which onco came down the Bealey, butj owing to tho disappearance of the yalloy wall, had ' gone down- the Otira. , |