Abstract
Geometry of the boundary of the serpentine in the south-east Lizard indicates that it is a sheet. The serpentine sheet rests on hornblendic gneisses and their migmatized equivalents; the upper part of this basement represents a thrust-sole in which bodies torn from the base of the serpentine are enclosed. Coastal erosion of rocks beneath the serpentine tends to marginal collapse of the unsupported sheet, so that slipped masses may conceal its base.