It is perhaps stretching a point to describe this site as a promontory fort. Castle Rock Of Muchalls is a promontory lying about 1½ kilometres south of the village of Muchalls, on the coastline between Aberdeen and Stonehaven. It's a pleasant clifftop walk of under an hour from Muchalls, notable for its spectacular coastal scenery of stacks, arches and skerries.
Carnmore lists this site as a possible encampment, which suggests that it was a temporary fortification. However, details are very sparce, and there are now no visible remains that can be related to an encampment.
The promontory is reputed to have been "protected on its landward side by a deep ditch, now partially filled in" (Name Book 1865).