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Forming the coalfields

coal deposits map
Coal was deposited in tropical swamp forests that flourished in shallow fresh water lagoons - when the 'tectonic plates' of this area were nearer the Equator.

Coal in Kent and Nord - Pas-de-Calais
The coalfields show just how much geological history Kent and Nord - Pas-de-Calais have in common.

The same seams of coal run deep underground on both sides of the Channel, showing that - in the Carboniferous era millions of years ago - the section of the earth's crust that forms the whole region lay much nearer the Equator, and was a tropical swamp.

Kent and France were in the Tropics
The map (left) shows how much of Northern France and the British Isles were once a shallow tropical lagoon, lying to the north of a chain of mountains - long since eroded away.


The incredibly slow process by whicjh layers of coal were formed.

Coal from plants - layer by layer
Rivers rushing down from the mountains fed fresh water into the warm shallow lagoons, where primitive fern-like plants flourished - see diagram left. A - Each year, plants died, and new ferns and leaves grew - plant debris accumulated on the bottom of the lagoon - B.

When the land sank due to movements of the earth's plates - and the weight of accumulated plant remains - salty seawater flooded the lagoons and killed the freshwater plants - C , covering them with sand or mud. - D

The cycle would continue, building up thick layers of plant remains, alternating with mineral layers - E.

Pressure and heat
After millions of years, the weight of layers covering the lower dead plants would start to change them into coal - by heat and pressure,


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Places to visit:
Historic Mining Museum - Lewarde, nr Douai

Nature parks:
Saint-Amand - Nature Park in former coalmining area

Related background information
Early coal-mining
Rise and fall of coal-mining
How the English Channel was formed




A-Z © Copyright 2001 Invicta Media Last updated 19th February 2001