Peat

Dark, waterlogged plant matter, cut in blocks from fens, bogs and moors with special spades, then stacked to dry and burned as fuel. The right to cut it, called turbary, was valuable where woodland was scarce. In east Norfolk peat was dug on a large scale from the twelfth century, and the flooded pits later became the Norfolk Broads.

Sources: broads-authority.gov.uk