Canterbury and Westland. 325 



tains, passing for a considerable distance along the higher central 

 range. Similar indentations are also found to exist towards the 

 Canterbury plains, but they have either been already filled by alluvial 

 deposits forming fertile valleys, such as the Kaituna^valley, or they 

 appear in the form of a lake (Lake Forsyth). In examining the 

 nature of the rocks of which the system under consideration is 

 composed, we find that, with the exception or" a small zone at the 

 head of Lyttelton Harbour, the whole is composed of volcanic rocks ; 

 that the deep indentations are ancient crater walls, so-called calderas, 

 into which a channel with precipitous walls, the barranco, leads ; and 

 that they consist of a series of lava-streams, with^ agglomerates 

 consisting of scoriae, lapilli, ashes, and tufas interstratified with them. 

 These beds have all a qua-qua versal dip, that is to say, they all incline 

 outwards from the centre of the cavity. The higher mountains in the 

 centre consist also of volcanic rocks of a similar composition, which 

 appear either horizontal or, when the direction of the lava-streams 

 composing them can be ascertained, are found to flow into the 

 calderas previously formed, from which we can at once conclude that 

 they are of younger origin. Finally, we find mostly in or near the 

 centre of these deep cavities, or calderas, either a small island or a 

 peninsula stretching so far into these harbours. They consist also of 

 volcanic rocks, having been preserved above the last centre of eruption. 

 This last sign of vulcanicity is on a smaller scale than the previous 

 ones. The whole of Banks' Peninsula, measuring along its longest 

 axis from north-west to south-east, has a length of 31 miles, with a 

 greatest breadth of 20 miles, and if we do not take the numerous 

 indentations into account, it has a circumference of 88 miles, which 

 corresponds closely with that of the base of Mount Etna. 



In the Geological Map attached to this report, I have marked with 

 circles, more or less perfect, according to the preservation of the lips 

 or rims, all the principal centres of eruption which I have traced 

 during my surveys, and I have no doubt that the remnants of others, 

 which have escaped my observation, and are for the greater part 

 concealed under younger lava- streams, will be found during future 

 examinations. On the line between Lyttelton Harbour and the head 

 of Akaroa Harbour, the highest portion of the Peninsula is found 

 where the small craters of Mount Herbert and Mount Sinclair are 

 situated. Having thus given an outline of the general features of the 

 volcanic system under consideration, I shall now proceed to offer a 

 short history of its origin, which will at the same time serve as an 

 explanation to the general sections added. 



