Intra-Palaeozoic earth movements
|Green, G W. 1992. British regional geology: Bristol and Gloucester region (Third edition). (London: HMSO for the British Geological Survey.)|
Much of the region lies within the Midlands Massif or Microcraton, which is bounded on the south by the Variscan Fold Belt. The massif was a stable region during the Palaeozoic Era, apparently undergoing only epeirogenic (i.e. largely vertical and extensional) movements up to the time of the Variscan orogeny. Evidence of Caledonian earth movement in the Lower Palaeozoic rocks is scanty, largely due to the restricted outcrop of the older rocks. The epeirogenic movements continued throughout the Devonian and early Carboniferous until the onset of compressional deformation during the Variscan orogeny. This last event had the most profound effect on the Palaeozoic rocks, and structures that developed during it and continued to influence sedimentation throughout the succeeding periods.