326 PEOCEEDINGS OF THE GBOIOGICAL SOCIETY. 



oblique lamination, without permanent or definite order of succes- 

 sion in the beds, and the upper by more persistent horizontal bed- 

 ding. Shells abound in the lower, and are rarer in the upper division. 



The general features of the Red Crag are too well known to 

 require more than brief mention. In the central area there occurs 

 at the base of the lower division a bed of phosphatic nodules (the 

 so-called " coprolites "), varying in thickness from a few inches to 

 one or two feet. This bed is slightly developed between Manning- 

 tree and Harwich. At Dovercourt 1 have found remains of it with' 

 its characteristic fossils on the top of the cliff; but it is in the 

 district between the rivers Orwell, Deben, and Aide that it is most 

 largely developed, and most profitably worked *. This bed often 

 has an underlie of large blocks of London-clay Septaria, and of 

 large, entire, and fresh-looking flints derived from the Chalk. In 

 this shingle are also found a considerable number of the larger shells 

 entire, particularly an abundance of Cardium edule, Pectunculus 

 glycymeris, Cyprina islandica, Trophon antiquum, &c., whilst the 

 Septaria are drilled by boring mollusks, and both Septaria and 

 flints are covered with Balani. Large pebbles of sihceous sand- 

 stone, balls of concretionary dark fossihferous sandstone, rolled and 

 worn bones or teeth of Cetacea, Sharks, &c., and occasionally frag- 

 ments of the older rocks, are also met with in this bed. At a 

 pit at Trimley, near PeKxstow, I found subangular fragments of 

 ]jOwer Greensand chert, a large fragment of red granite, and frag- 

 ments and pebbles of siliceous sandstones. Although this shingle 

 and accompanying fragments of the older rocks are generally con- 

 fined to the base of the lied Crag, large blocks of angular flint and 

 seams of phosphatic nodules occasionally occur in the overlying beds. 

 Quartz pebbles are met with in the Red Crag, but they are rare. 



This basement bed sometimes thins out f , and at other times 

 divides into two beds separated by a foot or two of shelly crag. 

 Sometimes also thin seams of phosphatic nodules occur 3 or 4 feet 

 above the lower bed, and separated from it by a bed of comminuted 

 shells, as at Foxhall, "Waldringfield, and, in places, at Sutton. Di- 

 spersed nodules may, in fact, be found through the whole of the 

 Red Crag. 



Above this basement bed are a series of beds more or less fossili- 

 ferous, forming with it the lower division of the Red Crag, which is 

 generally from 10 to 15 feet thick, and rarely attains a thickness of 

 from 20 to 25 feet. These beds are very irregular, not persistent 

 for long distances, often mere lenticular masses, and are marked 

 by the more or less constant occurrence of oblique lamination. This 

 lamination has not a constant direction. It varies to almost all 

 points of the compass. The dip is generally from 12° to 32°. A 

 common dip is about 22°, N.W., N.N.W., and N.E. It is in the 

 upper part of the lower division that false bedding is most general. 



■* Particularly in the district which surrounds the central mass of the Coral- 

 line Crag of Sutton. 



t In the cliif at Bawdsey this basement bed is altogether or almost wanting, 

 whereas half a mile inland it attains a thickness of from 2 to 3 feet. 



