The nappe theory in the Connecticut Valley region: thirty-five years since Jim Thompson's first proposal

The nappe theory in the Bronson Hill anticlinorium of the Connecticut Valley region began with Jim Thompson's analysis of the structure of Skitchewaug Mountain in 1954. By 1968 the theory included the recognition of three giant fold nappes formed early in the Devonian Acadian orogeny, with tens of kilometers of east to west overfolding. In the 1970s detailed remapping suggested that the system included not three but four fold nappes. Some of the rocks previously assigned to the Skitchewaug level proved to belong to the Bernardston nappe beneath the Skitchewaug. Although sheared and attenuated fold limbs were part of the nappe theory before 1980, it was only after this that major thrust faults were considered to be important. -from Authors