C.— 9

14

calculated on the basis of an assumed yearly production, provided the approximate amount of coal, probable cost of working, and probable selling-price are known, and in most cases is found to be much less than would be supposed by those unacquainted with the manner in which compound interest accumulates. In any case, the value of the field, even a hundred years hence, is problematical, and only on the most favourable suppositions of any consequence. (8.) General Remarks. A fear lias been expressed thai the clearing of the land in what is known as the Brighton Block would result in the coal being set on fire. Of this there is nol the least danger over the greater part of the Brighton Survey District. and more particularly over the area fit for settlement, for all the coal is under a thick cover of Miocene rocks. The area in which bituminous coal and anthracite outcrop is poor land, mostly at somewhat high elevations, and not suitable for settlement. Even if the bush on this land were felled and burnt, the most ordinary precautions would obviate any risk of the coal being set on fire. The geology of the Brighton district is interesting, and of some importance. The detailed survey of the area between the Grey Coalfield and the Buller will give much information concerning the order of succession and age of the various coal-measures. It is likely, indeed, that the district contains a key to the stratigraphical relations of the New Zealand coalfields. These, Hector and McKay maintain, in the main belong to one great system, the Cretaceo-tertiary, which they suppose contains coal in two closely adjoining horizons only. Hutton and other geologists are inclined to place the, coal-seams in two or more formations of different ages, though in a recent paper* by Marshall, Speight, and Cotton a return to the views of Hector and McKay is to some degree noticeable.

*"The Younger Rock-series (if New Zealand," Trans, of N.Z. Inst, for 1910, Vol. xliii. KM I, pp. :t7B-407.

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