Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/484

 Bawdsey and Felixstow. Flat pieces of the thin limestone seams of the Coralline Crag are common in the Red Crag around Tattingstone, where the same reef-like structure of the Coralline Crag is shown at Park Farm (fig. 24) ; and I have found some small fragments even in the Red Crag at Walton.

Fig. 24. — Pit at Park Farm, Tattingstone, near Ipswich.

Another old Coralline-Crag reef forms the nucleus of the ridge of hills from Gedgrave and Orford to Iken and Aldborough. The Red Crag abuts against its flanks, and its summit is capped by the Chillesford clay ; but although the Red Crag can be traced close up to these hills, the cliff-line is nowhere exposed. At the same time the erosion of the Coralline Crag adjacent to this old reef during the Bed-Crag period is seen in the section given in fig. 15. It is probably the littoral zone of an old shore connected with a higher part of this reef or islet that is indicated by the Mya-bed of Mr. Fisher.

Having described the Red Crag and Chillesford series in their typical and special area, and followed them as far as Aldborough, we come to more debatable ground. Some geologists have referred the crag at the Aldborough ballast-pit to the Norwich Crag, and others to the Red Crag. The next sections, however, which are only two miles further north, present far more definite characters. Their relation to the Norwich type cannot be doubted ; and to that group they have always been referred. It remains now to be seen whether there are sufficient grounds for considering the Crag in the area north of Aldborough to be newer than the Red-Crag series, or whether it is to be considered a synchronous deposit, with differences of character depending upon local conditions.

We have already noticed three ridges of Coralline Crag — one at Tattingstone, a second at Sutton, and a third extending from south of Orford to Iken and Aldborough. The first two are small, and the Red Crag wraps round them without any change of character. The third is more important and makes a greater break in the Red Crag, which nevertheless reappears on its eastern flank, although