Structure and origin of the Malvern Hills

Abstract

Abstract and Introduction Half a century ago T.T. Groom in 1899 and 1900 published his two papers on this subject. Groom built on his predecessors, as must the writer: the most important sources were J. Phillips, Holl and Callaway, but there were many others. Groom's views seemed to gain immediate acceptance; and have not been seriously opposed except by Falcon (1947) , who doubts the existence of an eastern boundary fault and would put the main uplift before Upper Coal Measures time. Groom repeated his theory in Geology in the Field (1910). For many years the writer, while deeply indebted to Groom for his facts, has held a view very different from Groom's as to the essential structure and the origin of these hills. Groom stressed the role of compressive and elevative stresses of Armorican date; and he limited tensile stresses, believed to be Tertiary (1910, p. 736) to the eastern fault. The writer, accepting Armorican and Tertiary movements as the main agents, claims that the Armorican were more varied and much more extensive than Groom envisaged. According to Phillips (1855) , ‘the Malvern Hills form one of the most beautiful and singular ranges of mountains in the world’: they are indeed remarkable in several ways. Topographically they are peculiar, both because they stand up so magnificently above the low plain of the Severn and because they are so serrate in outline in contrast with the levels of the upland plains; and geologically they are noteworthy, not only for these reasons, but also because they consist of such coarsely crystalline Archaean rocks in so extremely narrow an area, in direct contact on one side with Mesozoic, on the other with Palaeozoic sediments; and, in the writer's view, because they owe their structure and emplacement to movements of four different periods, and of two quite different kinds—tangential compression and tension; and lastly because they owe their survival as hills to having been dropped down as well as pushed up.