GEOSUFFOLK RIGS
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THE WESTLETON BEDS – A CASE FOR RIGS H. B. MOTTRAM Introduction In most exposures, Norwich Crag is a well sorted sand. This is typical of nearshore environments that include both beaches and tidal flats. Genuine “crag” (shell deposits), muds and gravels do occur but are the exception rather than the rule. About 1·9 million years ago the Norwich Crag was coming to an end and some gravely deposits were laid down in ENE Suffolk and in parts of Norfolk. These deposits are often referred to as the “Westleton Beds” but strictly speaking they not a discrete set of beds, they are a local variant. The gravelly deposits occur in several ways. Descriptions and accounts of these are given in the references listed. The different gravelly occurrences are summarised in Table 1. It is not necessarily an exhaustive list but it sets out some of the most significant types of occurrence. Discussion Although we have a good understanding of gravels deposited by rivers our understanding of gravels deposited in the sea is much poorer. Also, most gravels that occur within the geological record were deposited by ancient rivers eg the Kesgrave Formation. To find examples of rip-channels in the geological record is difficult enough but to find gravelly examples of them is, as far as I know it, impossible. Therefore it is important to preserve some of our “Westletonian” ones. As for gravelly tidal inlets, well they are even more unique. The sites therefore have educational value. There are several issues to unravel and as knowledge advances we will want to re-evaluate earlier work so the sites are clearly important to ensure continuing research. The sites also have historical value. Prestwich used the term Westleton Beds in 1871 and 1890 while the Geological Survey (noteably Whitaker, Dalton and Blake) mapped and described Pebbly Series (1884–1890). Both sets of workers considered that they were separate from the Norwich Crag. Although Solomon added a little more information in 1935 (he actually used the term Westleton Series) it was really Richard Hey’s thoughtful work in 1967 that kick-started current interest. There are currently two RIGS, the cliffs at Dunwich and at Minsmere. They are accessible from public car parks that have toilets and refreshment facilities. They fit comfortably alongside other publicly accessible countryside amenities. In conclusion, sites exhibiting the so called “Westleton Beds” in ENE Suffolk have great RIGS potential.
References Hey, R. W. (1967). The Westleton Beds reconsidered. Proc. Geol. Assoc. 78: 427. Mathers, S. & Zalasiewicz, J.(1996). A gravel beach-rip channel system: the Westleton Beds (Pleistocene) of Suffolk, England. Proc. Geol. Assoc. 107: 57.