The surface rocks of Grasmoor are composed primarily of the Ordovician Kirkstile Formation. These are laminated mudstone and siltstone, typical of the Skiddaw range. There is no history of mining beneath the slopes of Grasmoor. The bowl of Dove Crags is one of the largest glacial combs or cirques in the Lake District, yet has no tarn, but dry hollows noted as curious by. This cavity has originated or been enlarged by a very large landslip (rock slope failure)which over at least the last 20,000 years has been displacing the Liza Beck northwards, narrowing Gasgale Gill valley and provoking the unusually extensive scree slopes of Whiteside.