| Popis: |
Analysis of the available data has resulted in the production of two subcrop maps for the subsurface of Essex, a north-south gravity interpretation and a geological section. The stratigraphical sequence is exemplified by the Canvey Island Borehole. There are no other boreholes in Essex which have been geophysically logged and which penetrate through the Cretaceous succession. The gravity interpretation, together with the borehole provings, indicate an east-west, elongated downwarp in Devonian rocks north of the Variscan Front and a complementary upwarp to the north in the vicinity of Ware. The lack of borehole and seismic reflection data impedes a more detailed knowledge of the subsurface, which, in view of the large Colchester earthquake, may be structurally complex. Minor magnetic anomalies, near Bishop's Stortford, relate to bodies within the Lower Palaeozoic or Precambrian rocks and an estimated 5 km of non-magnetic sediments are likely to be present beneath most of Essex. |
