100 
GEOLOGY. 
eighty-two degrees towards the west, and contained near the inter¬ 
secting veins inchoate hornblende crystals. Higher np in the 
mountain range, traps and hornblendic granites occurred, as I 
judged from angular pieces of those rocks brought down by the 
torrent amongst the sandstones, cherts, and amphibolites, of which 
its principal gravel consists. 
The continuation of Mount Mantell, on the southern banks of 
the Warwick, consisted, as far as I could judge from the rocks in 
situ and from pieces brought down by the mountain torrents, of a 
succession of highly crystalline slates. In the bed of the Maruia, 
where it breaks through the Cannibals’ Gorge, we find, close to 
the depression, beautiful mica slates, chlorite schists of different 
colours, quartz schists, old clay slates, cornubianites, and spotted 
slates (fleckschiefer) with sheaf-like concretions of a blackish green 
substance (fahlunite ?), and also grey wake sandstones, green and 
red Maitai slates, and micaceous clayslates, alternating with small 
quartz layers, the latter three without doubt brought from the 
Spencer mountains, and identical with the rocks seen in the 
sections from Nelson to Queen Charlotte Sound. The rocks in 
the. opening itseli:, besides granite, are hornblende and quartz 
schists, exhibiting the same strike and an almost vertical dip. 
Another interesting fact is the total absence of crystalline lime¬ 
stone on the western side of the central chain, or south of the 
Buller, on the eastern side; this zone appearing therefore to 
be confined to the north-eastern side, where it is so largely 
developed. That the Southern Alps continue to exhibit the same 
structure as the chains before described, has ben proved to me by 
the rocks collected by Mr. Eochfort on the saddle between the 
Hurunui and the Taramakau, and by those rocks taken from the 
beds of the mountain torrents which fall from Mount Cook, which 
Mr. J. Mack ay had the kindness to bring to me on his return from 
the lower parts of the West Coast. Mount Cook itself consists of 
mica slates, chlorite and quartzose schists, as well as of graphite 
slates and old clayslates. 
Amongst the boulders in the Grey we meet with small pieces of 
nephrite, the greenstone of the Maories, derived from veins in the 
slaty rocks, but the locality in which it is principally found to the 
south of the Grey is the Arahaura river. It is also found all alono- 
the coast, from Milford Haven to the Punakaiki cliffs, north of the 
Grey, in the boulders on the sea shore, whence magnificent 
specimens are obtained. The Maruia plains are of a lacustrine 
formation, and were evidently the bed of an old lake laid dry, 
partly by the accumulation of detritus brought down from the 
mountains, and partly by upheaval, as evidenced by the terraces 
on both sides of the plains. In some of the vertical sides of these 
terraces, formed by the action of the rapid river, which has often 
changed its bed, we observe deposits, consisting, near the margin of 
the old lake, of sand and gravel, mixed with boulders of every size. 
