151

Whilst the other seams strike regularly through,
this last seam of 2 ft. 4 in. exhibits the important and
interesting fact that it runs out in the drive, so that
we may infer that it becomes, as is usual, broader in
its downward course towards the centre of the basin.
But had we not even this proof, we might conclude,
from the nature of the whole deposits that we have
here, the outgoing upper end or edge of the basin.

Below these last seams we find again—

ft. in.
Blackish slaty shale ... 0 3
Brown earthy shale ... 1 4
Laminated coal ... 0 7
Drift coal, with patches of white clay ... 2 1

As other beds, belonging to this carboniferous
series, but of a different character, lie below the last
mentioned seam, we find, by calculation, that although
the upper members of these coal-bearing strata are
denuded, and most probably, as before mentioned, to
a great extent, yet, notwithstanding this fact, we
meet here 34 ft. 8 in., in which seven seams of lami-
nated coal are imbedded. If the coal-bearing strata
already show such a well-developed character, there
can be no doubt (of course always taking into
consideration any possible local disturbance, but of
which at present no signs are observable) that more
towards the centre of the basin large stores of this
precious mineral are only awaiting the enterprising
hand of man to be brought to light.

Below the last seam we meet a new deposit, argil-
laceous sand, in which small patches of drift coal are
imbedded, sometimes surrounded by white clays.
Insensibly, these sands change into a rock, which,
although much altered by decomposition, exhibits all
the characteristics of greenstone tufas. Imbedded in
these soft beds are large boulders, often several tons
in weight, consisting of a dark augitic greenstone. As
the greenstones which we meet amongst the palæozoic
rocks, partly interstratified with them, partly break-
ing through them, are of great age, the occurrence
of tufas, belonging to them, will be another proof
that these coal measures belong to a remote period.

Below these tufacious beds another small coal seam
became exposed, but instead of showing the usual
character, it had been changed into coke or cinder, with
prismatic partings.

It is therefore evident that these greenstone tufas
were deposited when still at a very high tempera-
ture, probably during the eruption; the changes
from coal into coke-like beds being, without doubt, at
the same time assisted by boiling water under high
pressure.

Below this bed, and after passing through several
strata of white clays, alternating with small layers of
ironstone, a second but larger cinder bed is reached,
resting upon clays partly calcined. That the green-
stone eruptions took place at several distinct periods,
is proved by a new and larger greenstone tufa bed,
equally full of boulders, often of large size and all
of the same nature. This latter deposit is divided
by small streaks of carbonaceous matter from a stra-
tum of argillaceous sandstone, replete with layers and
veins of quartz, which form the bottom beds of
the coal measures. It lies unconformably against
the edges of a true greywacke sandstone, the strike
and dip of which correspond with the general strati-
graphical character of the rocks in the range south
of the coal measures. I observed this latter stratum,
which from its greater hardness had better resisted
the action of the waves than the greenstone tufas
above it; also in some other places in the valley of
the Kowai.

As the seam and other strata in the drive, standing
at a high angle towards the horizon, are only overlaid
by deposits of the great drift formation, of a thickness
of 15 to 20 feet, it is natural that they are very liable
to be affected by the percolation of surface water,
with which in fact we had great trouble in making the
drive.

Almost everywhere the strata were so much satu-
rated, that it was with the greatest difficulty that in the
drive I was able to observe any difference between the
coal seams and the shales and dark clays near them,
and only by drying the coal in the sun, when it again
became hard and shiny, was I able to fix with accu-
racy the position and thickness of each seam. As
this investigation, undertaken on behalf of the Pro-
vincial Government, has shown us that we have here
only the outcropping end or edge of the coal basin
before us, it would be unwise to begin to work the
coal at such a spot, because, as is generally the case,
the seams are not of that regularity which we may
expect to find more towards the centre of the basin,
and although coal may be worked at almost every
angle, it will be more convenient to choose a spot
where a lesser dip of the carboniferous beds gives not
only greater facility in working the seams, but also
offers more advantages for raising the fuel.

The best spot therefore to work these coal measures
will be more towards the centre of the basin, and I
would recommend borings to be undertaken at the
southern corner of Mr. Watts Russell’s sheep yards,
where I have no doubt, the dip of the seam will be
inconsiderable.

If, as I anticipate, the coal-bearing strata have not
been disturbed, we shall meet them there again below
the surface of the plains at between 250 and 300 feet,
or lying at an angle of 5 to 10 degrees towards
the north.

I append to this report, first:—A section showing
the results of the works undertaken for the Provin-
cail Government; second:—A geological map of the
Kowai river coal fields, upon which I have marked
all the spots where I observed rocks belonging to the
carboniferous series; together with a horizontal sec-
tion of the coal measures with their probable position;
and third and lastly, a vertical section of the coal-
bearing strata which have been passed through by the
drive.

As the coal has already been practically tested, its
value for steam and forging purposes has been fully
proved; and I am certain, that an analysis made to
ascertain its chemical constituents will show a very
large amount of carbon contained in it.

APPENDIX

TO THE REPORT ON THE KOWAI COAL MINES,
Dated January 20th, 1862.

Geological Survey Office,
Christchurch, Sept. 11th, 1863.

On returning from a re-examination of the ligni-
tiferous beds at the head of McFarlane’s stream, I
visited the scene of my former labours in the Kowai,
in order to see if the mining operations undertaken by
the Kowai Coal Mining Company would offer me any