Kettleness was the site of one of the alum quarries which shaped this coast in the 18th and 19th centuries. Local woman had noticed that clothes washed in streams that ran off the cliffs hereabouts didn't lose their (expensive) dyed colour. Therefore, they theorized, there must be something in the water that helped fix the dye to the cloth. They were right; aluminium salts were washed out of the Whitby mudstone alum shale and made the water a dilute mordant; a dye fixative.
After a certain amount of experimenting, a process was discovered that allowed the mordant to be separated from the rock. The shale was quarried, piled
into a conical pyre with layers of brushwood and set alight.
The oil content in the shale allowed the pyre to smoulder away for
months. The burned shale was then boiled in vats of human urine until
the alum salts crystallized out of the liquor.
The quarrying left the coast hereabouts looking rather strange:
in places Kettleness looks almost lunar:
Gutters carved out of the local sandstone carried runoff into the sea.
There isn't much left to see; when the alum works closed the buildings were probably cannibalized by the locals, some of what was left will have have fallen into the sea. Here are what looks like floors and walls of the alum works now close to the cliff edge:
A view over some of the ruins, Runswick in the distance.
This stone-lined tunnel that runs into the hillside (purpose unknown).
The quarrying resulted in some 20 million tons of Jurassic shale being hacked out of the cliffs hereabouts which of course caused some fine fossil finds, this one - Rhomaleosaurus cramptoni - now adorns the Natural History Museum in London: