Geology Reference
In-Depth Information
Atmosphere
Solution
Evaporation
Animal
respiration
Hydrosphere
Plant
metabolism
Burning of
fossil fuel
Erosion
and
weathering
Biosphere
Precipitation
Plants
Animals
Accumulation
of
marine
shells
Decay of plants
and
animal residues
Lithosphere
Limestone
Dolomites
Coal
Peat
Oil
Natural gas
Figure 1.1.1. The carbon cycle. From Kim and Kissell 1988, p. 18.
Geologic Distribution of Coal Seams
A
lthough coal deposits are known to have formed in every geologic period, the development of land plants in the
Silurian and Devonian provided source material for peat and coal. The periods of greatest coal formation were the
Carboniferous and the Cretaceous/Tertiary (Cooper and Murchison, 1969; van Krevelen, 1963).
Carboniferous Coals
The formation of coal deposits required abundant plant material, a suitable climate, areas for accumulating peat and
means of preserving the carbonaceous sediment. These conditions were prevalent over large areas during the
Carboniferous (Pennsylvanian in the United States) period. During this period, large areas of what is now the
Eastern USA, Europe, Asia, and Australia were located near the equator and had a climate that was tropical to
subtropical with mild temperatures, high humidity and heavy rainfall, without cold winters, or extended dry periods
(White, 1925).
