Hurrox.—On the Thames Gold Fields. 279 
` grey tufaceous sandstone, full of mundic, as at Keeven's Point and Kapanga, 
thus proving this rock to extend in a narrow belt from the sea level to 
1,600 feet altitude." I do not see how finding a rock at three different places 
in a line, and at very different altitudes, can prove that it runs in a narrow 
belt. It seems to me that the absence of the rock on either side of the belt 
should be first proved ; but I have myself traced this rock for several miles in 
a direction nearly at right angles to the line indicated by Dr. Hector, and it 
must be remembered that if the gold should be found to run only in a narrow 
belt 16 would by no means imply that the bed-rock did the same; for the 
distribution of a rock is one thing, and the distribution of gold in that rock is 
quite another thing. Не also says (Le. р. 92) that “the auriferous reefs are 
: generally in the decomposed rock, and, as at Shortland, have a general direction 
parallel with the boundaries of the formation, or N. 40° E.” But in his 
map of the Coromandel district he shows his * greenstone tufa" formation 
running in a nearly north and south direction, and without a single boundary 
approaching to a N. 40? E. direction. As Dr. Hector has not attempted 
to map his formations at Shortland, I cannot tell where he supposes the 
boundaries to lie in that district. 
At Tapu, he says (¿e., p. 98) that “the reefs are in bands of greenstone 
porphyry, which intersect the slates with a prevalent north-east strike." But 
most of the claims (except those in the slates) are situated in a brecciated rock, 
which is certainly not intrusive, and could not intersect slates ; neither ean it 
be interbedded with them, for the slates here are nearly vertical, and strike 
east and west. As Dr. Hector has not mapped any of these bands I do not 
like to speak positively on the subject, but their oceurrence in the way that he 
describes them appears to me to involve a physical impossibility, and, although 
I made a careful survey of the district, I saw nothing that would lead me to 
adopt his opinion. 
Mr. Davis asserts (/.c., р. 99) that south of Hastings the older бан 
formation strikes north and south, while the more recent tufas are nearly 
horizontal; but, from a personal inspection of the locality, I am convinced 
that Mr. Davis mistook jointing for bedding, there being no planes of strati- 
fication visible, while his more recent tufa is but the older one decomposed. 
I made the same mistake myself in my first report on the Thames. Mr. Davis 
also appears to think that, as a tufaceous breccia is found at the Thames 
enclosing fragments of tuff or breccia, it necessarily proves two distinct 
formations. But this is by no means the case, for it is a common phenomenon 
in all submarine volcanic districts, When an eruption is over, the vent fills 
up and consolidates, and a subsequent eruption breaks this up into fragments 
and scatters them around. An example of this may be seen in the Auckland 
Domain, in a cutting through basaltic tuff of newer pliocene or pleistocene age. 
