128 Transactions. 
Several cones with a crater-like character show us the different centres of 
eruption; whilst around them, and extending from one to the other, marine 
sands have formed barriers, enclosing tracts of low land favourable to the 
formation of peat swamps. 
Pitt’s Island is formed of the same volcanic rocks, but it is more hilly, 
and does not present the same strange aspect as the main island. 
The rocks submitted to me, with the necessary explanations, by Mr. H. 
H. Travers, afford a clear insight into the structure and formation of these 
islands, and to them I shall refer when speaking of the different characters 
of the rocks. 
The oldest rocks visible oceur near Kaingaroa, and stretch in a west and 
east direetion towards the north-eastern corner of Chatham Island. They 
dip towards east at an angle of about 30°, and consist of micaceous clay- 
slates, silky, and of a pale green colour. They are traversed by veins of 
quartz which has the appearance of being auriferous. Similar rocks occur 
in our Southern Alps of New Zealand, on the eastern slopes of the Moor- 
house range, and on the south-western slopes of Mount Cook. Smaller 
outcrops of this rock occur at the north-western corner of the large salt- 
water lagoons, and at Wangaroa or Port Hutt. Some beds of limestone 
fringe the south-western shores of that lagoon, to which, judging by their 
mineral character, we may assign a very high age. This limestone is of a 
white colour, and very crystalline; its structure is somewhat vesicular, but 
as the specimens submitted to me are rather small, it is difficult to assign to 
this limestone its true age, although, in its general character, it has all the 
appearances of a palæozoic limestone. 
As before stated, the main eminences of the principal island are formed 
by basaltic rocks, which contain often large concretions of hornblende, 
augite, and chrysolite. At their base, basaltic rocks, which often form 
perfect cones, and tufa beds, are met with, which in lithological character 
are identical with those of the same age in New Zealand. 
The collection of rocks from Pitt’s Island is far more complete, enabling 
me to examine the fossils which they contained, and thus assign to them 
their true age. 
The lowermost rocks resemble those from the main island, already de- 
scribed, of a basaltic and doleritic character. On them, and on the western 
side, repose palagonite tufas, identical with those associated with our tertiary 
doleritic rocks i in the Malvern Hills, Mount Somers, &e. On them, again, 
agglomerate containing large pieces of voleanie breccia cemented together 
Dads RPM a slight admixture of carbonate of lime and only 
to a tufa ou Ww whitish limestone, enclosing g great quantities 
TESORO MORE 
EU enka ee 
