The Red Crag and Norwich Crag formations in eastern Suffolk

The Red Crag Formation of eastern Suffolk was deposited in structurally controlled basins during the Pree-Ludhamian, Ludhamian and Thurnian stages. A regression during the Thurnian was followed bya transgression during the Antian/Bramertonian Stage, with the Norwich Crag Formation resting unconformably on strata as old as Upper Cretaceous. A regression during the Baventian Stage led to the formation of a complex of shoreface gravels (Westleton Beds) and intertidal clays at the mouth of a river which flowed from the English Midlands to reach the sea in the Southwold area. The Chillesford Clay Member was formed penecontemporaneously 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 correlated with the reflectors respectively at the base of the Westkapelle Ground, Smith's Knoll and Winterton Shoal formations of the southern North Sea.