Abstract
Preface:
The Kawarau Gorge is, in a number of respects, one of the more striking geomorphological features of the South Island of New Zealand. Its position in the Clutha drainage system is shown in Figure 1. It is entrenched between the Pisa and Crown Ranges to the north, and the Remarkable Carrick Range to the south, extending for a distance of some 20 miles. The Kawarau River flows through the gorge after draining glacial Lake Wakatipu, which is the largest lake in New Zealand, and the Arrow River system is also tributary to the Kawarau just above the gorge, which serves as their outflows east-ward to the Upper Clutha Basin.
In spite of the obvious interest of early explorers, and the comments and conjectures of later geologists, the features of the gorge have inspired relatively little close fieldwork. Moreover beyond a number of introductory accounts, little has been published on the Kawarau Gorge.
The purpose of this study has been to initiate a detailed examination of some aspects of the physical characteristics of the gorge, in particular of the broad, vividly clear flights of terraces, whose remnants occur as striking staircases in the Gibbston area. These are the major landforms, extending vertically over almost 1,000 feet of valley sides, that have long excited the interest of visitors, but it is considered at this stage vital for any advance to be made in understanding the recent geological history of the gorge that more precise measurements should be taken of the several levels found throughout the course of the river.
Such measurements have formed the basis of the work of this investigation and from them a first analysis has been attempted.
Such an investigation has more than local significance, as has been pointed out by Sparks (B W Sparks, “Geomorphology”, London 1960, p2.): “Essentially any study of the evolution of landforms attempts to reconstruct a succession of pictures of the relief at different periods. Alterations of relief are usually caused by changes of base-level and climate. Thus the reconstruction of former base-levels and of the landforms related to these base-levels, by means of (marine) and river terraces and long profiles is one part of the study, while the study of landforms produced for example by glacial and periglacial conditions is the other.”
In the field, these two series of factors have been taken into account. In the Kawarau gorge both terrace-and-profile studies, and glacial-periglacial studies are particularly relevant. Their interaction has in fact produced a complex of landforms that presents no simple picture. Only detailed investigations can unravel the story behind the landscape of today. It is the intention of this thesis study to provide such an investigation, and in so doing to undertake the necessary detailed measurements. Only on this basis can an attempt be made at correlating the landforms observed, leading towards a coherent story of the development of the Kawarau Gorge.
It is at the same time appreciated that a number of alternative postulates may in some cases be held to follow from the field data. Meanwhile it is to stimulate closer examination of the Geology and landforms and to provide a step forward towards further theoretical discussion of the problems of the development of the landforms and river system of Central Otago in southern New Zealand, that this study is put forward.