Discussion

Abstract

Dr M. F. Ridd asked what were the authors9 views on the possible southern extension of the Malvernian trend. If the e–w-trending Alpine folds of Dorset were followed into Devonshire, they swung towards the south-south-west or the south. There the folds and faults had amplitudes of up to about 300 ft and were best appreciated by contouring the unconformity at the base of the Albian. There was also evidence for n–s pre-Albian folding, judging from the sub-crop pattern in the vicinity of Axminster. This anomalous trend resulted either from a deflection of the Alpine folds around the Dartmoor block, or else it was due to eastward gravitational gliding off the block, or, as seemed most likely, it resulted from Alpine re-activation of buried structures that extended north-north-east to join the Malvern Hills. The Authors replying to Dr Ridd, said there had been considerable speculation about the importance of a 9Malvern Line9 in Britain, notably by Hawkins (1942, <i>Q. Jl geol. Soc. Lond.</i><b>98,</b> xlix–lxx), but few detailed data were available from other areas. In the present state of our knowledge they would prefer not to speculate about the existence of such a line, or try to relate it to movements responsible for either of the Malvern boundary faults. The interesting structures from the sub-surface of Dorset and Devonshire described by Dr Ridd might prove an important contribution to the elucidation of this problem. Dr M. Brooks outlined the results of recent geophysical work in the Malvern Hills