(click image to enlarge)
On both sides of this division of the valley, and indeed in the greater part of North Dale also, are alternate projections and recesses, each corresponding to the other in so striking a manner, as to leave no doubt as to their having been in times long past one solid mass, which having been riven asunder by some mighty convulsion of Nature, has left the valley as it now appears.
(Henry Belcher, Scenery of the Whitby and Pickering Railway, page 54)