In Zululand they are chiefly anthracitic. The fossils include several species of Glossopteris among them: Glossopteris ' See C. L.
The proportion of this residue is greatest in the more anthracitic or drier coals, but a more valuable product is yielded by those richer in hydrogen.
P. 273), differences in composition are mainly original, the denser and more anthracitic varieties representing plant substance which has been more completely macerated and deprived of its putrescible constituents before submergence, or of which the deposition had taken place in shallow water, more readily accessible to atmospheric oxidizing influences than the deeper areas where conditions favourable to the elaboration of compounds richer in hydrogen prevailed.
South of the line between Galway and Dublin the coal is anthracitic, while north of this line it is bituminous.