A Contour Map of the Sub-Carboniferous Surface in the North-East Midlands

Summary A combination of data from seismic surveys and deep borings has provided a basis for a tentative contour map of the rocks beneath the Carboniferous. This surface falls from outcrop in Charnwood, and around 2,000 feet below sea level in the southern Fenland, to at least 10,000 to 11,000 feet near the Humber and beneath the Lower Carboniferous gulfs. As far as is known gradients are fairly gentle, reflecting the control of the Lincolnshire–East Midlands Shelf area. The steepest falls are on the north-eastern flank of the Charnwood–Mountsorrel area where there may well be major faulting. The very limited penetrations of the sub-Carboniferous floor show quartzites, possibly Cambrian, in the middle parts of the area, and sheared rocks comparable with Precambrian in the south and west.