The Little Beck Alum cave is man-made. Alum was mined here between 1660 and 1809. There are many nearby alum caves, but they are hidden by woodland growth and pools. The steps lead to the top of a domed spoil heap, and another cavern.

Littlebeck Alum Works operated from 1690 to 1809, making it one of the earliest in England. The Works were owend by John Matthews who became bankrupt and sold the enterprise. John Danby purchased the Alum Works and managed to reduce the costs but by 1805 the competition from larger works forced their closure.

Between our visits to Littlebeck in 2016, 2018 ane 2024 there has been much management activity in Little Beck Wood, not least of which is the construction of wooden steps and board walks over the muddiest areas.

Alum is not the same as aluminium. Aluminium's full name is aluminium chlorohydrate. It presents as a small molecule and its ions are readily absorbed by the human body. Alum, also known as potash alum, has a larger molecule and is more stable. It is not absorbed by the body and is therefore less dangerous. It is a colourless crystal comprising a double sulphate of aluminium and one other element, usually potassium or ammonium.

The alum mined in Littlebeck was aluminium sulphate. This was significant in North Yorkshire in the 17th century as England's economy centred around wool and linen. Yorkshire was reputed for its vast sheep farming market, which produced wool, and flax (linseed) cultivation was part of Yorkshire's subsistence farming from which was produced linen. The gentry of that century had a high regard for bright and colourful clothing and the vegetable dyes that had been used prior to the use of alum did not fix the dyes, which rinsed out when the clothing was washed. This drawback was trounced by the use of alum which was a mordant, i.e. an inorganic oxide that combines with a dye to fix the colour in the material.

Much of the mine has been filled in with water, visible as the Coast to Coast path extens along it. In the 17th century alum was used mainly as a fixing agent for dyed cloth produced by the textile mills. The process of mining alum at Littlebeck was to heap the mined alum shale into large mounds. They were then fired in a clamp made up of a brushwood heap 3-4 feet high, upon which the alum deposits were piled, again 3-4 feet high. Once the firing began more alum and brushwood were added until reaching up to 60-90 feet high and 200 feet in diameter. It was then left to smoulder.

After about 9 months the alum shale was leached for a time and the alum solution was drained off whilst it ran along liquor troughs to an alum house, where the water was evaporated from the solution in evaporating pans. Human urine and burnt kelp were conveyed from a wharf built on the River Esk near Ruswarp, two miles south of Whitby's estuary, to provide an alkali which caused precipitation of the alum crystals, the finished product of the Littlebeck alum works.

Coast to Coast Trail Guide

"Hiking the Coast to Coast" is a digitally enhanced eBook available from Apple Books for all people who have either a Mac, an iPhone or an iPad, and is designed to accompany you on your walk of the Coast to Coast path. The trail guide contains Ordnance Survey maps and other advanced mapping features, step by step directions, hundreds of colour photographs, details of the route, its conditions in different weather and research snippets relating to places of interest along the way.