Description: ÒProduction of coal in North America in 1913 and approximate outlines [in red] of coal fields other than ligniteÉ Each dot represents 1 per cent of worldÕs production. [x] Represents 1/2 to 1/10 per cent of worldÕs production. [v] Represents less than 1/10 per cent of worldÕs production. — Department of the Interior, 1921 Source: Department of the Interior , World Atlas of Commercial Geology (Washington, DC: Department of the Interior , 1921) Plate 2 Map Credit: Courtesy the private collection of Roy Winkelman |
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