TRANSACTIONS FLORA OF THE CORALLINE A N D RED CRAGS OF EAST SUFFOLK F. W.
SIMPSON
THE Coralline Crag of East Suffolk is the earliest of the Suffolk Crags, and is a rieh fossiliferous deposit of the Late Pliocene. It is often cemented together by corals and the remains of other animals to form a hard rock which was once quarried for building stone. This use can be seen in several churches : Chillesford, Orford, and Ramsholt are examples. The Coralline Crag can be examined in old excavations at Sudbourne, Orford, Gedgrave, and Shottisham, and in cliff exposures at Aldeburgh and formerly at Ramsholt. It is usually covered by later deposits and rarely lies at or very near the surface over large areas, except at Sudbourne Park. The Red Crag is a much later deposit of the Lower Pleistocene and extends over a greater area of the coastal districts of East Suffolk, roughly south of Aldeburgh and into North Essex. It is usually observed as a sandy and shelly rieh reddish-brown deposit, and can be traced inland along the river and stream Valleys—in the Aide and its tributaries at Saxmundham and Parham ; the Deben at Charsfield and Clopton ; the Finn at Witnesham ; the Gipping at Battisford ; the Stour at Nayland and Bures ; the Brett at Layham ; and the Box at Boxford and Leavenheath. The shelly crag is covered over much of this area by glacial drift. However, it is found that some crag sands are no longer " shelly " and have been " deealeified " by the action of rain-water, and can easily be mistaken for glacial drift. North of Aldeburgh is the Norwich Crag, which used to be exposed in the cliff at Thorpeness. This crag extends into the Waveney Valley and across the valley into Norfolk. It comes to the surface at Sizewell and Leiston Common. There are important excavations at Holton, near Haiesworth, and exposures in the cliffs at Easton Bavents, near Southwold. Deealeified Norwich Crag sands occur in the Blyth Valley at Blyford, Wenhaston, Blythburgh, Reydon, and elsewhere in the area. The Chillesford Beds are the latest deposits in the Crag sequence. These deposits consist of shelly sands, pure sands, pebble beds, and clays, and occur near the surface only in small areas at Chillesford and near Aldeburgh. Deposits related to this epoch occur north of Southwold.