The 1827 ‘History of Northumberland‘ here says:
The Scotch Street was generally a mere track-way, though in some boggy places it is paved. Till the Ponteland road was made it was the common road from Scotland, by Elsden, to Newcastle. By some it was called the Salter’s-way: hence the term Salter’s-nick, which is the name of a narrow pass through the Shaftoe-crags, and which, in 1552, seems to have been called East Shaftoe-dore, where one of the [men of Bolam’s] watches was then stationed; and there are curious earth-works.