Glenthorne (grid reference SS800497) is a 13.3 hectare geological Site of Special Scientific Interest in the parish of Oare within the Exmoor National Park, on the border of Somerset and Devon, notified in 1989.

Glenthorne is a Geological Conservation Review site because of the Trentishoe Formation of the Hangman Sandstone Group.

The Hangman Sandstone represents the Middle Devonian sequence of North Devon and Somerset.

[1] These are unusual freshwater deposits in the Hangman Grits, which were mainly formed in desert conditions.

[2]