Discussion on a latest Cretaceous hotspot and the southeasterly tilt of Britain

Abstract

K. Thomson writes: Cope's (1994) paper on a Late Cretaceous Irish Sea hotspot and its influence on the present-day drainage pattern of the British Isles has focused attention on the importance of regional erosion in the southern Britain. However, there is additional evidence which points to deficiencies in Cope's (1994) erosion map, invalidates his results within the area of the proposed dome and extends the area affected by erosion into the North Sea, Scotland, Ireland, Scandinavia and the basins of the Atlantic continental margin. Onshore there is evidence for 1.3–1.7 km of Cenozoic erosion ( Green 1989 ; Hillis 1993 ) outwith the zero erosion contour of Cope (1994) . In addition, the heavily inverted Cleveland basin has been shown to have experienced over 2 km of erosion ( Hillis 1995 ) whilst Cope (1994) has the zero contour passing through the basin. Further afield, kilometre-scale erosion has been demonstrated in the Southern North Sea (Bulat & Stoker 1987; Bray et al. 1992 ; Hillis 1993 , 1995 ), the Inner Moray Firth ( Hillis et al. 1994 ; Thomson & Hillis 1995 ), the Scottish Highlands ( Lewis et al. 1992 ), Ireland ( McCulloch 1994 ), the Norwegian/Danish Basins (Jensen & Schmidt 1992; Japsen 1993 ) and the Western Approaches ( Hillis 1991 ). Taking the regional evidence for Cenozoic erosion into account shows that there is no evidence for an erosional ‘bull’s eye’ centred on the Irish Sea. Furthermore, as thermal anomalies, hotspots can produce only transient uplifts because when the thermal anomaly decays, the uplift decays with it. This has the effect of returning