 The sequence east of Lynmouth used to be referred to as the "Foreland Grits", and was thought to be somewhat older, and hence lower in the sequence, than the Hangman Grits

The Trentishoe Member exhibits unusual deposition at the Glenthorne Site of Special Scientific Interest.The formation comprises slates and limestones of marine origin and sandstones and slates with a shallow marine or deltaic origin.In the west, the Ilfracombe Slates are subdivided into (oldest at base, youngest at top)