Air Survey of the New Zealand Alps

Abstract

The Southern Alps, forming the eccentric backbone of the South Island, and extending some 250 miles up and down its western side, have been in process of gradual exploration from the early days, by prospectors, local surveyors, sheep-run holders, hunters and mountaineers. But extensive areas of the inner and higher portions of the region have remained scarcely known and entirely untraversed, the remoteness and inaccessibility of some parts being extreme, and the western side notorious for its almost impenetrable bush. No adequate survey of the region has ever been carried out, and even the position of many of the chief peaks, obtained where visible from the low country by intersection, can only be considered approximate. The Department of Lands and Survey has never as yet undertaken a comprehensive topographical survey of the main range of the Alps; and the New Zealand Geological Survey, on account of stringent economy and shortage of staff, has not thought fit to embark upon a detailed investigation, whether for scientific or for uncertain economic purposes. In a country of so small a population, and with a very limited tourist industry, the public, including mountaineers, geologists or other scientific travellers, have had to be content with a general map on a scale of 1 : 253,440, or 4 miles=i inch, except for the Mount Cook Alpine Regions sheet on a scale of 1 : 100,000, or 1 mile =23 inch (New Edition 1953). But of the general (4 miles=i inch) map only the northern half has so far been published, the portion west of longitude 1700 still being in the draughting stage. There has, how? ever, been an increasing demand of late for adequate topographical maps, and problems in connection with the geology of the Southern Alps have remained an important consideration. Consequently, the time seemed ripe for the formulation of some plan that would enable both topography and geology to be reconnoitred and mapped as quickly and economically as possible. Only by aerial means could such a project be carried out. After discussions in Wellington between the Air Operations Branch and the writer, a beginning was made in 1953 by a squadron of the R.N.Z.A.F. (Wigram), who kindly undertook to include a small project of air photography in its routine training fiights. This first project, essentially for glaciological purposes, covered by means of a vertical mosaic the Tasman, Hooker, Franz Josef and Fox Glaciers in the central Alpine region; but unfortunately, owing to delay until after the arrival of the first winter snowfall, there was much masking of important surface features, and a great opportunity was largely wasted. In 1954 the Central Photographic Establishment of the R.N.Z.A.F. at Ohakea, North Island, was good enough to accept my proposals for an oblique photographic cover of as much of the main range as possible, but in the event likely to be confined to the northern portion, between Harper Pass l on the north-east and Fyfe Pass at the south-west end. Oblique photography, relatively to a vertical cover, implied a great reduction in flying time, and, moreover, the provision of photographs in which one could better observe the geological structures visible in mountain faces