Minor tectonic structures in the Skiddaw Slates of Raven Crags, Mungrisdale, northern Lake District

Abstract

Tectonic minor structures of four phases of deformation, D1 to D4, are described from the Loweswater Flags division of the Skiddaw Slates on Raven Crags, near Mungrisdale. D1 structures, which are not common, are tight folds and isoclines with steep plunges of variable orientation. D2 structures, the dominant feature of the crags, are upright folds and steeply inclined cleavage, of anomalous north-west trend over most of the crags. D3 structures are sub-horizontal folds and gently inclined cleavage occurring on the limbs of D2 folds. D4 structures, recorded only from the southern end of the crags, are minor north-south flexures and intermittent fracture cleavage. This report is partly intended to provide a background and field notes for parties visiting the locality.