Were supposed to be accumulations of floating wood, are denudations of Miocene deposits containing layers of brown coal with full stems of trees.
It is abundant, for example, in the plastic clay of the Brown Coal formation at Littmitz, near Carlsbad, in Bohemia, at which place it has been extensively mined for the manufacture of sulphur and ferrous sulphate.
Thick; the lower part of this is mainly fireclay and sandstone, the upper part is weathered clay with thin layers of brown coal and shale.
They are also preserved in basins on the western plateau, as shown by brown coal deposits passed through in the Lake Phillipson bore.
In the south-western parts a succession of strata, described as the Brown Coal or Lignite formations, intervenes between the chalk and the boulder clay; its name is derived from the deposits of lignite which occur in it.
Lignite or brown coal includes all varieties which are intermediate in properties between wood and coals of the older.
Types, may be distinguished, and these, with the two extremes of brown coal or lignite and anthracite, form a perfectly continuous series.