Formation of Coal
 Coal is considered a Fossil Fuel. Coal is an organic sedimentary
rock which forms from the decaying of plant materials such as
moss, ferns and parts of trees (dried out peat bogs).
Fossil Fuels:
 Non-renewable fuels that formed long ago from the
remains of plants and animals.
 The origin of fossil fuels, starts with photosynthesis. Note
that if the reaction runs in reverse, it produces energy and
releases carbon dioxide and water.
Reference:
Tarbuck and Lutgens
Pages 46
Formation of Coal
 Coal is a sedimentary/metamorphic rock produced in swamps
where there is a large-scale accumulation of organic matter from
plants. Organic materials consist of carbon, oxygen, and
hydrogen. When plant material is buried, the hydrogen and
oxygen (H2O) is released leaving carbon.
 Coal is found in beds called seams, usually ranging in thickness
from 0.5 to 3m, although some seams reach 30 m. Two major coal
producing periods are known in geologic history. During the
Carboniferous and Permian Periods, the continents were
apparently located near the equator and covered by shallow seas.
This type of environment favoured the growth of vegetation and
rapid burial to produce coal.
Formation of Coal
The Formation of Coal Involves Several Steps:
1) Formation of Peat.
 Swamps are areas where organic matter from
plants accumulate. As the plants die and get
buried they compact to become peat. With time
and more compaction, almost all of the water is
lost and three different grades of coal result.
2) Formation of Lignite Coal.
 Compaction of the peat due to burial drives off
volatile components like water and methane,
eventually producing a black-colored, organicrich coal called lignite .
 Soft brown coal which consist of about 40%
carbon and do not burn efficiently.
Peat
Burial
Compaction
Lignite Coal Seam
Burial
Formation of Coal
The Formation of Coal Involves Several Steps:
3) Formation of Bituminous Coal.
Burial
 Further compaction and heating results in a more
carbon- rich coal called bituminous coal.
 Soft coal which consist of about 85% carbon and
burns readily but produces a lot of smoke.
4) Formation of Anthracite Coal.
 If the rock becomes metamorphosed, a high grade
Compaction
Bituminous
Metamorphism
Burial
coal called anthracite is produced.
 Hard dark coal which consist of 90% to 95%
carbon and burns very hot and clean. Forms as a
result of metamorphic conditions.
 Anthracite coal produces the most energy when
burned.
Anthracite
Coal Seam
Sample Problem
Use a diagram to explain the four
stages involved in the formation of
anthracite coal.
Answer:
From peat to lignite there is burial and
compaction.
From lignite to bituminous there is greater
burial.
From bituminous to anthracite there is
metamorphism.
Water and gases are released during all
stages.