1) The bed of coal was a layer or stratum of coal and the term is much older than has been implied.
The first OED reference is 1802 and it might be thought that ‘bed’ in this sense was a meaning coined by geologists. It actually has a long history in mining contexts, and two Hipperholme documents point to its use in the Elizabethan period. It occurred in 1581 and again in 1591 one myne of coals within the greaveship of Hipperholme, with all rights and the several colebeddes to the same mine apertainyng, lying and being, Northowram. In 1665 coal mines in Crigglestone had several coalebedds thereto belonging. It is clear that from a very early date the boring methods used by colliers made them aware of the existence of beds of coal at different levels and of different quality, and in each region these were given distinctive names, e.g. 1694 paid for getting on the Low Bed
paid for getting on the Crow Bed, Farnley
1713 towards the Soft Bed coals on the rise side, Shibden. This is another term which provides evidence of the miners’ geological awareness.