PEaSXWICH CRA.G-BEDS OP SUFFOLK AiSTD NORFOLK:. 353 



Sutton (and possibly the Sudbourne) reef, and scattered over the bed 

 of the E.ed-Crag sea (fig. 23). The circumstance of the occurrence 

 of large masses of flint, covered with Balani, and of pebbles derived 

 from distant formations indicate transport, probably by ice-action ; 

 for the flints are of considerable size and perfectly unrolled. They 

 seem to have been dropped where they are found; and it is a question 

 whether the Balani with which many of them are covered may not 

 have been attached on the coast before their removal. This removal 

 necessarily requires a certain depth of water, as also would the accumu- 

 lation and reconstruction by sea-currents of the mass of sand and 

 comminuted shells forming a great portion of the E,ed Crag. The 

 character of the fauna of the Red Crag is in accordance with these 

 conditions. Littorina littorea, Purpura lapillus, Cardium eduJe, 

 Pholas crispata, Teredo norvegica, and Mytilus edulis clearly indicate 

 shore-lines ; whilst the several species of Astarte, Trophon, Turri- 

 tella, Cardita, Nucula, together with the common Pectunculus gly- 

 cymeris, Pecten opercularis, Mactra ovalis, and others, are confined 

 to the laminarian and deeper zones. 



If we suppose a shoal to have been formed in one part of this 

 sea-bed, and subsequently, owing to a change in the currents, to 

 have become subject to a scouring action in another direction, the top 

 of this shoal would be thrown forward in successive laminae, steep in 

 proportion to the velocity of the water, and thus form oblique lami- 

 nation, such as is so common in the Eed Crag. Eresh currents may 

 afterwards have removed other shoals and spread them over these 

 obliquely laminated beds in a series of horizontal layers, which, 

 in their turn, may have been scooped and hollowed out, and the 

 depression filled by a newer accumulation — a case not at all un- 

 common in the Eed-Crag district. This, again, may have been 

 planed down and re-covered obliquely by a fresh removal of ad- 

 jacent shoals. In this way we may have an infinite number of 

 repetitions of the same materials. This constant shifting and re- 

 adjustment of materials would, at the same time, lead to the heavier 

 portions, such as the bones, the pebbles, and the phosphatic nodules, 

 being thrown down and left behind when the lighter materials were 

 removed, and would thus tend to accumulate them in the basement 

 beds where we now generally find them. 



The consequence of these reconstructions is that a large propor- 

 tion of the shells are worn or broken, and the mass of them are 

 finely comminuted. The presence of some entire and double shells 

 shows that there were more sheltered places. That there were also 

 intervals of repose and quiet is evident from the circumstance that 

 thin horizontal seams of very finely laminated clays and sand were 

 occasionally formed ; these we find interstratified at places with the 

 beds of shelly crag. 



I have mentioned that, at Bawdsey, I found a bed of micaceous 

 sandy clay with laminae covered by ripple-marks, which laminae 

 were continued in regular succession for a thickness of several feet. 

 They were formed probably in shallow water (fig. 7). In some cases 

 beds of clayey sands seem to have been raised above the sea-level, 



