27

Section of Strata at C, 1692 feet above the level of the sea, Dip to N.W. 15 degrees.

Fine grained Grey Sandstone (thickness unknown) | | 53 | 10½ |

Thus giving, Coal | ... | 15 | 7 |
" Shale | ... | 1 | 1½ |

Thickness of seam | ... | 16 | 8½ |

The bands of shale in this seam are far from being a disadvantage, for they form partings which will facilitate the working, but it is probable that the two lowest seams of one foot and one foot three inches will be lost in the working, leaving 13 feet 4 inches or 13 feet of available coal. This is the finest seam I have seen in the district, and the quality is equal to any. I lighted a fire to try it, and had some difficulty in extinguishing it, as the small coal took fire and burnt so freely that at one time, I feared the seam itself might take fire from it. At Cc I again measured the seam 13 feet above the water in the stream, but I could not get to the bottom of it. You will observe from the direction of the arrows that the strata here dip both east and west, and the whole appearance of the place shows that the Gorge has been rent open by violent upward movement. The general dip here both ways is about 15 degrees.

On the very top of the precipice at D, on the right bank of the north branch there is a large seam, but as I have only seen it from the other side of the Gorge, I cannot tell either its quality or thickness, but as seven or eight feet, at least, were visible above the tops of the trees, there is no doubt of its being large. About a mile above the junction on the left bank of the branch, I found the following section, viz.:-

Dip to S. S. W. five deg.
This seam is 70 or 80 feet above the river.

Below the 16 feet seam in the Gorge there is a sort of slaty formation, and below this again nothing is found but igneous rocks, so it is quite evident that this is one of the lowest, if not the very lowest seam in the coal field.

From these observations I have come to the following conclusion, viz.:-

That as the west side of the mountain between the Wariatea and the Waimangaroha Rivers wherever it has been tried, is composed entirely of rocks belonging to coal formation, except in the lower part which is covered by the more recent beds of soft sandstone and marl, without any indication of igneous rocks, the lower part of the coal field at all events must exist there.

And as it has been shown in the Gorge of Waimangaroha and the neighbouring streams, that large and valuable seams are found in the lower part of the field, it is almost certain that these seams exist on the western side of the mountain, at a much lower level than the edge of the table land. But as they do not show themselves cropping out there, being covered by the enormous accumulations of debris, it will be necessary to search for them by sinking or boring. Diagram 9 will illustrate this: in it the 16 feet seam is shown in its true position in the Gorge of Waimangaroha, and the surface is from actual survey, and may be depended on as moderately correct. For the sake of illustration I have continued the seam from the Gorge to the edge of the table land, though the dislocations are merely to show that for part of the distance (judging by the surface) a good deal of disturbance may be expected, and that the remainder is moderately level and regular. What I wish particularly to illustrate, is that it is almost certain the seams exposed in the neighborhood of the Gorge, will be found on the western side of the mountain, probably many hundred feet below the edge of the table land, and in that position and for some considerable distance to the east, north and south of it, they may be expected to be moderately regular, and in a favorable position for working. But there is every reason to expect a good deal of irregularity even here, and I do not hope to find in any part of this coal field the uniformity met with in many parts of England where there are tracts of thousands of acres having, scarcely a dislocation more than a foot or two, and the angle of dip not varying more than two or three degrees over the whole extent. In a field which has evidently undergone such violent convulsions this cannot be expected. But seams such as we have here, will compensate for many disadvantages. Now as to a certain level (say 800 feet) on the mountain side, no regular seam has yet been met with, I would recommend borings to be made at some convenient place about that level where it is quite certain it is impossible to form an angle, and regular,-probably in the neighborhood of the river Rapid, N (see Plan 2, Sheet 11, and Diagram 8). Let the boring if possible pass through the whole coal formation: it is impossible to form an opinion how deep that is, but I think there are sufficient data to justify the conclusion to which I have come, that some of the finest seams in the series will be found here, at an elevation of less than 800 feet above the sea.

Suppressing a number of seams to be found, which is very probable, the next question would be, which of these ought to be worked first? Other things being the same it would be the best to commence at the lowest, for the work necessary to win would serve the same purpose for those above, at the same time the length of the drift or tunnel, necessary for bringing the water and coal out of the mine to the railway on the hill-side, would be increased in proportion to the depth, though this would probably be compensated by the mouth of the mine being so much nearer the base of the mountain, thus shortening the railway and what is of more importance reducing the elevation. There are other things more purely mining, which would have to be considered, in determining the order of working the different seams. For instance, suppose we have a 16 feet seam in a certain position favourable for working, and above it, say 50 feet, another of 6 feet; if the lower seam is worked first and all the coal removed, of course the settling down of the superincumbent mass of strata to fill up the open space of 16 feet, would very seriously affect the upper seam and render it much more difficult, if not impossible to work, from being so much broken. And in places where much inflammable gas is generated, the difficulty would be increased, by its