Suffolk (TM 39724863)
The exposure at ‘The Cliff’, located at the southernmost end of the main Coralline Crag outcrop, shows a section of just over 3m of Coralline Crag. At the base of the section is about 0.6m of silty, unleached Coralline Crag belonging to the Ramsholt Member. The upper 2.4m of the section comprises leached bioclastic sands of the Sudbourne Member with large-scale cross-bedding. The boundary between the two members is indistinct; however, small silty clasts at the base of the Sudbourne Member are evidence of contemporaneous erosion. The Sudbourne Member at Gedgrave Cliff contains a high proportion of terrigenous sediment, mainly quartz. Along with the abraded condition of the bioclastic material, this reflects prolonged transportation of biogenic carbonate, which was derived from the north.
The interface between aragonite-leached and aragonite-bearing sediments lies a little above the contact between the Ramsholt and Sudbourne Members at Gedgrave Cliff, thus providing a rare opportunity to examine the Sudbourne Member with its aragonitic fossils intact.
Adapted from Daley and Balson, 1999.