Cenozoic uplift of southwest England

The uplift history of southwest England is inferred using a composite dataset including marine and fluvial terraces and karstic data. The estimated post-Mid-Pliocene uplift increases eastward from ∼130 m in west Cornwall and ∼135 m in south Devon to ∼150 m in the Hampshire Basin. The post-Early-Pleistocene uplift likewise increases eastward, from ∼55 m in west Cornwall to ∼60 m in south Devon and ∼80 m in Hampshire. Landscape and thermochronological evidence also indicates Eocene uplift, caused by the British Tertiary Igneous Province magmatism; this component tapers eastward from ∼300 m in west Cornwall to ∼50 m in south Devon, with subsidence in east Devon. This uplift accompanied magmatic underplating; the mafic layer added to the basal crust thins eastward from ∼6 km in west Cornwall to ∼2 km in south Devon, evidently tapering to zero farther east. The laterally variable crustal properties caused by this variation in underplating have affected the post-Mid-Pliocene uplift; the study region is thus intermediate, in terms of crustal strength and landscape evolution, between central-southern England, with no underplating, and Ireland, where ∼10 km thick underplating has resulted in extreme Late Cenozoic landscape stability. The Eocene mantle-plume-related uplift is distinct from the post-Mid-Pliocene phase which, the modelling indicates, has been driven by surface processes and, thus, by climate change