Coal

Abstract

Coal-forming environments have existed since mid-Paleozoic time in areas where substantial quantities of vegetal matter are accumulating and being preserved. Widespread peat accumulation only became possible with the appearance of psilophyte vegetation during the Silurian, which accounts for the first Devonian coals and then the extensive Carboniferous seams. Evolving Mesozoic and Tertiary vegetation occupied an ever expanding range of environments. Today tropical swamps and marshes are undergoing the most rapid accumulation of peat, with rates in Borneo of 17 m (55 ft) in 4000 years (Stach et al., 1975, p. 15); but peats are also forming in temperate and even polar regions, and at high altitudes. The same geographic diversity is apparent in the origin of coal (Fig. 12-1). The majority of early seams were laid down in humid tropical regions, but in Permian and later times coal formation shifted to temperate and polar regions (Diessel, 1970).