The geological results of gravity and magnetic surveys in the Malvern Hills and adjacent districts

Abstract

AbstractDetailed gravity and vertical force magnetic surveys in and around the Malvern Hills are described, and the results of determinations of densities and magnetic properties of local rocks are presented. The geophysical surveys indicate that the Malvern axis is a broad anticline involving basement rocks and that the folded basement extends northwards at shallow depth under the Storridge anticline; it cannot be traced further north under the Abberley Hills. Areas of surface Pre‐Cambrian rock are interpreted as comprising intensely folded and faulted axial portions of the major fold, which is assumed to be of Armorican age. On the basis of the shallow depth to basement directly north of the Hills, and by analogy with the situation in the southern Malverns where Llandovery strata overstep the Local Cambrian succession, it is concluded that the Cambrian rocks were largely removed from the Storridge area as well as from the Malvern Hills area following a period of pre‐Llandovery tectonism. To the west, the basement surface dips at about 30° to a depth of at least 5,000 ft.Cook and Thirlaway's (1955) suggestion that the Eastern Boundary Fault is part of a step‐fault complex is accepted, and their interpretation of the configuration of the Worcestershire Triassic basin is not significantly amended in the present account.