A Fading Memory: The North Yorkshire Coastal Alum Industry in the Light of Recent Analytical Field Survey by English Heritage

Abstract

For over 250 years from 1604, the North York Moors were the centre of the English alum industry. The principal use of alum was as a mordant to fix and enhance the colour of dyed cloth. It was made by quarrying, burning and steeping vast quantities of shale to produce an impure solution of aluminium sulphate; then, at alum houses, the liquor was concentrated by boiling, and an alkali added to form alum. The North Yorkshire quarries exploited both inland and coastal shale exposures, but the most successful quarry/alum house complexes (alum works) were situated on or near the coast. Even when operational, the latter had to contend with periodic infrastructure losses from landslips and cliff falls; with closure, they now form a diminishing archaeological resource steadily sliding into the sea. This paper reviews the present understanding of the industrial process in the light of recent analytical field survey by English Heritage of four hitherto poorly recorded works, three of which are coastal. In so doing, it highlights the disproportionate loss of certain classes of features at the coastal sites, and advocates the need to do more to compare the latter to their inland counterparts, to place the industry in its wider British and European context, and to examine it from an economic as well as a technological perspective.