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of the Geological Survey and Mines Department, and a new estimate has been prepared based on information obtained from the Mines Department as to reserves of operating coal-mines and of closely drilled areas and from the Coal Survey as to reserves of the districts surveyed. The classification accepted —" measured," " indicated," and " inferred " —is that used by the United States Bureau of Mines and the Commonwealth Mineral Resources Survey. These terms are simply defined as follows : (1) " Measured coal" is coal for which tonnage is computed from dimensions revealed in outcrops, trenches, workings, and drill holes and for which the grade is computed from the results of detailed sampling. The sites for inspection, sampling, and measurements are so closely spaced and the geologic character is defined so well that the size, shape, and content are well established. The computed tonnage and grade are judged to be accurate within limits, and no such limit is judged to differ from the computed tonnage or grade by more than 20 per cent. (2) " Indicated coal " is coal for which tonnage and grade are computed partly from specific measurements, samples, or production data and partly from projection for a reasonable distance on geologic evidence. The sites available for inspection, measurement, and sampling are too widely or otherwise inappropriately spaced to outline the coal completely or to establish its grade throughout. (3) " Inferred coal" is coal for which quantitative estimates are based largely on broad knowledge of the geological character of the deposit and for which there are few, if any, samples or measurements. The estimates are based on an assumed continuity or repetition for which there is geologic evidence ; this evidence may include comparison with deposits of similar type. Bodies that are completely concealed may be included if there is specific geologic evidence of their presence. Although these terms are fairly close to the original terms —" proved," " probable," and " inferred " —it was considered better to use the clearly and specifically defined terms as above that now have wide international acceptance. The figures in all cases represent recoverable coal and not coal in ground.

The following are the total coal resources of the Dominion based on all available information at date (1950) :

It will be noticed, when compared with 1946 figures, that measured bituminous has increased, largely as a result of close drilling on the Buller field, and that a figure for inferred bituminous is presented. In both sub-bituminous and lignite the previous large quantities of proved coal have been considerably reduced simply because there was no evidence to support such figures as measured coal according to the definition of this term. In both cases, inferred resources have been shown, which in 1946 were confined to sub-bituminous. The over-all total of 1,112,000,000 tons is fairly close to the previous 1946 estimate (1,158,436,000 tons).

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— Measured. Indicated. Inferred. Tons. Tons. Tons. Bituminous .. 28,000,000 21,000,000 58,000,000 Sub-bituminous 52,000,000 45,000,000 502,000,000 Lignite 13,000,000 27,000,000 366,000,000 Totals 93,000,000 93,000,000 926,000,000