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The lignites of Eastern Texas have been mentioned in many places in this report in the description of the geology of the various parts of the region. They consist of the decayed vegetation which covered the region during the time that the lignites and their accompanying sandy and clayey strata were being deposited. In them are found the remains of trunks of trees, branches, and leaves, with impressions of reeds and other bog or swamp flora. In fact every lignite bed in the region represents the position occupied by an ancient swamp or coast lagoon. Probably most of the Texas lignites were formed in bayous and lagoons on the coast, and the vegetable matter was carried to them by rivers.

Such places were probably heavily timbered, and year after year the trees dropped their leaves and dead branches on the moist ground. Here they collected and were mixed up with dead reeds, moss, grass, etc. As the trees themselves died they also lay down in the same grave, and rotted in the same boggy waters as their leaves and branches, until often a great thickness of decayed vegetable matter had collected. Then, from some cause, either from a change of elevation of the land or an increase of rainfall, and hence of surface waters, these beds were submerged. The waters passing over them deposited sand and clay on top of the vegetable matter, and often reached a thickness of several hundred feet, compressing it by their weight into a solid mass. Hence the lignite beds as they now exist, overlaid and underlaid by sands and clays. It might happen that these same sand and clay beds that had been deposited over the vegetable matter may be again raised above the water level, form the bottom of another bog, collect more dead trees, leaves, etc., and again be submerged to be covered by sand and clay, in the same way