Where I live, coal was so abundant near the surface that you could have dug a hole in your garden and found it lying there. This coal was laid down during the carboniferous period when Bristol was somewhere over the Equator and the ecosystem was abundant with life. This coal is fossilised life.
Yet walk a few streets north-west and you find a band of red sandstone. By this time in its geological history, Bristol had drifted north towards the Tropic of Cancer and the area had become desert. No more fossilised life, no more coal – just scorched sand. Carry on further north and carbonate limestones return. The desert receded and life came back.
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