- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of Geology Exclusive of North America, Geological Society of America, Boulder, CO, United States
The folds, boudins, cleavage, small faults, cross joints and creases, basic dikes, and breccia zones in the lower and middle Devonian metamorphosed argillites, sandstones, and limestones exposed along the coast near Plymouth, southwest England, have been mapped and are described. The sequence of tectonic events inferred from the structures includes thrusting to the northwest causing "drag-folds," development of cleavage, intrusion of basic rocks along planes of weakness, formation of major undulations trending northwest, dip-slip faulting and formation of cross and oblique fractures, uplift and erosion, normal faulting and brecciation, and extrusion of lava. Movement probably continued intermittently into the Tertiary and later.