80 REPORT—1862, 
Tables I. and II. are compiled from statistics given in the ‘Otago Daily Times’ 
of April 6, 1862, and Table ILI. from those given in the ‘Otago Colonist’ of July 
15, 1862. 
On the Geology of the Gold-fields of Auckland, New Zealand. By W. Lavprr 
Linpsay, ID. & F.RS. Edinburgh, F.LS. §& F.R.GS. London, §e. 
The author had. personally made a geological examination of the Coromandel 
gold-field, in the province of Auckland, in February 1862, having previously 
spent several months on a similar survey of the Otago gold-fields. He described 
Coromandel as a different type of gold-tield from Tuapeka (Otago), and, as such, 
of interest as illustrative of the general geology of the New Zealand gold-fields. 
The main results of his observations and deductions may be concisely stated thus :— 
1. The geology of the northern gold-fields of New Zealand, including those of 
Nelson as well as of Auckland, does not differ essentially from that of the southern 
or Otago gold-fields (as the geology of the latter is described in his paper “On the 
Geology of the Otago Gold-tields,” save in so far as regards certain minor details. 
The parent slates, for instance, are in the north more frequently of a clay-slate or 
argillaceous character than in the south; the auriferous quartzites are frequently 
developed to an extent as yet unknown in Otago; the evidences of trappean dis- 
turbance are more numefous, and the metamorphism of the slates by the contiguity 
of the erupted or intruded traps better marked. Nor does the character of the 
gold differ materially, save in so far as, in certain localities, it is more generally 
associated with its quartz matrix. 
2. The Coromandel Peninsula consists mainly of a mountain ridge, running 
nearly north and south; the mountains haying a bold serrated outline, and varying 
in height from 1000 to 2000 feet. The valleys between the spurs given off laterally 
by this main or dividing range are of the character generally of ravines or gorges, 
occupied by mere mountain streams ; the “flats” or alluvial tracts at their mouths, 
and on the coast, are inconsiderable. 
3. This mountain-range consists apparently of slates of Silurian age, generally 
of argillaceous character, but greatly altered by contact with, or proximity to, 
numerous outbursts or intrusions of trappean and other rocks. ‘The mountains are 
so densely wooded, and so difficult of access, that it is only here and there in the 
gorges of the streams that sections of these slates may be examined. In these 
sections the slates are frequently found to resemble Lydian stone or the slaty 
varieties of basalt (such as clinkstone); while they are disposed more or less 
vertically, their irregular upturned edges affording the most convenient and 
abundant “pockets” for the detention and storage of the alluvial gold washed 
from the higher grounds. 
4, [Local geologists describe the fundamental rock of the Coromandel mountain- 
system as granitic, and the granite as forming here and there the “aiguilles” of 
the dividing ridge. The author met with no granite zz situ; nor did he discover 
granitic boulders or pebbles in the boulder-clays of the auriferous drift, or in the 
shinely beds of the mountain streams about Coromandel Harbour. | 
5. The Coromandel slates are characterized by their prominent and numerous 
quartz “reefs,” consisting of auriferous quartzites. Here and there, where the 
dense vegetation admits, these reefs are met with in situ, frequently as “dykes,” 
standing prominently above the general level of the slates ; sometimes forming the 
top of the dividing ridge itself. The proximity and abundance of such quartzites 
are sufficiently indicated by the immense numbers of huge quartz-boulders or 
blocks which bestrew the low ground and occupy the ravines and gorges, which 
blocks are characterized by comparative angularity. The quartz is frequently of 
the porous, light, spongy character so prevalent in the gold-fields of Australia, 
Nova Scotia, California, and other auriferous countries ; and its colour is frequently 
buff, brown, ochrey, or vermilion, the result, anparently, of different degrees of 
ferruginous impregnation. 
6. The auriferous drift is mostly of the charac.er of the newer or upper Tertiary 
drifts of the Otago gold-fields, consisting essentially of—u. variously coloured clays ; 
b. houlder-clays, also variously coloured; and ¢. gravels, of the “chopped slate” 
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