Most currently available estimates of coal resources and reserves in the United States were prepared to determine only general areas of coal occurrence and thicknesses of beds. Such estimates were usually accompanied by coal analyses to indicate the coal rank and to a much lesser degree, other quality parameters of the coal deposits. Estimation of coal tonnage was accomplished by simple but time-consuming arithmetic and/or geometrical procedures, which usually involved the use of hand-drawn maps and the polar planimeter. For many regions of the United States, data and/or manpower available were so limited that only broad estimates of coal resources could be made. As a result, our national coal resource data base is quite limited in both scope and detail.

In the future, computers will be used extensively to process such data as depth, thickness, quality, environmental factors, and other parameters associated with coal resources. Computers can be programmed to generate many kinds of maps and numerical tabulations. By the use of point data (e.g., drill holes, outcrops) resources can be classified according to any desirable classification system, such as thickness categories.

Most procedures currently used to evaluate coal resource and reserve data rely upon point-of-observation spacing only for geologic assurance of coal occurrence. Several major studies are underway to develop geostatistical methods such as kriging and the use of variograms, which facilitate evaluation of other uncertainties inherent in both quantity and quality data on coal resources. Thus, by use of computer processing and geostatistical methods, a more comprehensive understanding of the amount of characteristics of United States coal resources will be developed during the coming decade.

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