ABSTRACT
Coals are formed from the accumulation of vegetable debris in specialized environments. They range in age from Upper Palaeozoic to Recent. The rank of coal (peat, lignite, sub-bituminous coal, bituminous coal, semi-anthracite and anthracite, in order of increasing rank) and the degree of structural complexity are determined by the synsedimentary and post-sedimentary processes to which the vegetable matter has been subjected. The coal-bearing sequences tend to be so similar that when once a lithofacies (say, a sandstone) of a particular sequence (say, a Gondwana cyclothem) are met with, it is possible to predict the existence of coal of a particular rank.
