THE RED CRAG AND NORWICH CRAG FORMATIONS IN EASTERN SUFFOLK

The Red Crag Formation of eastern Suffolk was deposited in structurall y controlled basins during the Pre-Ludhamian, Ludhamian and Thurnian s tages. A regression during the Thurnian was followed by a transgressio n during the Antian/Bramertonian Stage, with the Norwich Crag Formatio n resting unconformably on strata as old as Upper Cretaceous. A regres sion during the Baventian Stage led to the formation of a complex of s horeface gravels (Westleton Beds) and intertidal clays at the mouth of a river which flowed from the English Midlands to reach the sea in th e Southwold area. The Chillesford Clay Member was formed penecontempor aneously at the estuary of the proto-Thames, further south. A further marine transgression occurred during the Pastonian. The Pre-Ludhamian, Antian/Bramertonian and Pastonian transgressions are tentatively corr elated with the reflectors respectively at the base of the Westkapelle Ground, Smith's Knell and Winterton Shoal formations of the southern North Sea.