Chapter Viii. the Energy Resources--Coal, Oil, Gas

(AND ASPHALT) 115

COAL 115

ECONOMIC FEATURES 115 World production and trade 115 Production in the United States 117 Coke 118 Classification of coals 119

GEOLOGIC FEATURES 123

PETROLEUM 127

ECONOMIC FEATURES 127 Production and reserves 128 Methods of estimating reserves 134 Classes of oils 136 Conservation of oil 137

GEOLOGIC FEATURES 140 Organic theory of origin 140 Effect of differential pressures and folding on oil genesis and migration 142 Inorganic theory of origin 143 Oil exploration 144

OIL SHALES 150

NATURAL GAS 151 Economic features 151 Geologic features 151

ASPHALT AND BITUMEN 151 Economic features 151 Geologic features 153