Volcanic pebbles in Pleistocene gravels of the Thames in Buckinghamshire and Hertfordshire

Abstract

SummaryThe incidence of volcanic pebbles in the gravels of the middle Thames basin is noted. The detailed petrography of volcanic clasts at two sites is described and found to be broadly similar to that of material from sites in East Anglia, thought to be of Welsh origin. The frequency of volcanic pebbles in the two areas is also similar. This evidence suggests that volcanic material was brought into East Anglia via the ancestral Thames.Records of volcanic rocks in the drift deposits of the upper Thames basin provide additional evidence of this route.