Today, the word ‘kelp’ is most commonly used to refer to several species of red, brown, and yellow seaweed, but in industrial contexts it refers to a glassy, oily product created by burning dried seaweed. Kelp was, and remains, an important source of sodium, potassium, and iodine, used in the processes of glass and soap manufacture, as well as in medicine and as a thickening agent in foods and toothpaste. From the 16th century, the major source of these chemicals was barilla, imported from Spain. Made by burning glasswort, barilla was purer and chemically more consistent than rival products, such as the kelp ash produced in Ireland and the Scilly Isles, but war on the Continent in the 18th century made supplies unreliable at a time of growing demand, to the benefit of local producers of kelp.
As the price of Scottish kelp rose from around £3 a ton in 1750 to a high of over £20 in 1810, more and more communities turned to kelp production, and at its height the industry employed around 10,000 families across Scotland. But in the decade following the Battle of Waterloo, with the lifting of punitive duties on Continental imports, prices collapsed: even the highest grade of kelp had fallen back to £3 a ton by 1827. The communities who had come to rely on kelp production for an income suffered great hardship, which contributed in turn to the subsequent history of emigration and clearance.
Imprints in the sand
Kelp production itself leaves few obvious or distinctive marks in the landscape, says Kevin Grant in his article on the subject published in the Scottish Archaeological Journal (see ‘Further reading’ box on p.23); hence the archaeology of this important industry in Scotland is in its infancy.
Excavating Staffordshire