326 Geology of 



The oldest rocks in Banks' Peninsula form a small zone of 

 palaeozoic sedimentary strata, possessing a slightly altered structure, 

 many of them forming beds of chert, others, peculiar light -coloured 

 brecciated schists ; however, sandstones and dark clay-slates are also 

 represented. This zone has a north and south direction, and reaches 

 to the southern watershed of McQueen's Pass, which leads from the 

 head of Lyttelton Harbour to Lake Ellesmere. ]S"ear this Pass, slates 

 appear as high as 600 feet above the sea-level. On the western 

 slopes of Castle Hill, the south-western continuation of Mount 

 Herbert, 2900 feet high, which rises so conspicuously above Lyttelton 

 Harbour, they reach an altitude of nearly 1000 feet, where they are 

 overlaid by the older lavas, forming the Lyttelton Harbour caldera. 

 Thus a sub-marine hill stood here in the young mesozoic sea, of 

 which portions of the summit and the slopes were gradually covered 

 by agglomerates and brecciated beds. These beds were formed during 

 and after the eruption of quartziferous porphyries, of which here and 

 there portions of the coulees have been preserved. Some of these 

 quartziferous porphyries resemble in every respect those from the 

 Malvern Hills and Mount Somers. They are also accompanied by 

 pitchstones. porphyritic from the presence of numerous well formed 

 crystals of sanidine or glassy felspar, and occasionally of garnets. 

 Other portions of the quartziferous porphyries, as for instance, the 

 whole coulee of which Manson's Peninsula is formed, have a rougher, 

 more trachytic matrix. They are full of grains and small crystals of 

 white greyish or smoky quartz. The brecciated beds have a hard felsitic 

 matrix, and the angular fragments of rocks enclosed in them belong to 

 a variety of eruptive rocks of many colours, and of different texture, 

 often forming a rock of striking character. They appear conspicuously 

 on the summit of G-ebbie's Pass, having been washed into cliffs of 

 picturesque forms, and covering the palaeozoic sedimentary beds from 

 one side of the Pass to the other. On the southern side of this Pass, 

 about 200 feet above the sea-level, occur two beds of shales with stems 

 and roots of carbonized plants, but too indistinct for recognition. 

 They are associated with coarse sands. Each of them is about 50 

 feet thick, separated by about 130 feet of loose conglomerate, the 

 whole standing at a very steep angle, dipping 76 degrees to the south- 

 south-west. They are situated at some distance from any locality 

 where the brecciated porphyry agglomerate upon which they appear 

 to rest, crops out. Thus they will be of more recent age than 

 the former ; however, no clear section is exposed anywhere, from 

 which this point could be settled quite satisfactorily. After the 



