260 A. 8f R. Bell— On the English Crags. 



clay, SaxicavcB, Pholades, and the boring Veneridce in their several 

 cists, with dead shells and cavities frequently occupied by Eellias, 

 and other bivalves, and in some places Mytili and -Cardia closely 

 packed, with other more solitary species intermixed, according to 

 depth, habitat, soil, etc. The univalves, as a rule, are less gregarious, 

 but even these would be found to occupy more or less certain zones 

 and favourable feeding-grounds. In other places heaps of dead 

 shells, parted bivalves, worn uriivallves, together with occasional 

 individual specimens in a more perfect state of preservation. Corals 

 would be found more plentiful at certain depths than others, and the 

 sea-bottom itself composed of comminuted shells, minute organisms, 

 fragments of Corals, Polyzoa, Echinoderms, and the debris of a vast 

 fauna ; sandy tracts bare of organic life occurring here and there. 



Now this is precisely the condition we find presenting itself in pit 

 after pit in the Eed Crag district, and we venture to say that there 

 is no part of a modern sea-bottom which we could not parallel 

 within reasoneible limits, in the bed of the ancient Eed Crag Sea. 



Before quitting this part of our subject we would only notice 

 further that those sections in the Coralline and Eed Crags which 

 have the greatest number of species in common, are those farthest 

 apart. Thus, to parallel Sutton and Gedgrave in the higher part of 

 the Coralline zone, we must look south to Walton-on-the-Naze, and 

 for the Grford and Sudbourne Crags, to the pits at Sutton (Eed 

 Crag) and Waldringfield, especially to the latter. All these pits are 

 miles apart. In those sections seen in juxtaposition, a« is the case 

 occasionally in Sutton parish, the greatest diversity prevails. 



We will now proceed to consider the position of the Eed Crag in 

 its relations to the Coralline and Fluvio-marine formations. "Many 

 geologists are of opinion that the different patches of the Eed Crag 

 formation are of different ages, although their chronological arrange- 

 ments cannot be decided by superposition." Several attempts in this 

 direction have been made. Mr. S. Wood enumerates, in a valuable 

 paper upon the Structure of the Eed Crag (Quart. Joum. Geol. Soc, 

 1866), three stages, which he denominates the Walton, Sutton, and 

 Butley Crags. Mr. Wood, junior, finds four beach stages and one 

 horizontal, in all five stages. Messrs. Prestwich and Jeffreys, by 

 eliminating " extraneous " fossils, and by the reduction of species into 

 varieties, have brought the whole, including the Fluvio-marine and 

 Chillesford series, into one palseontologicai group, but admit that 

 some division in the lower (or Eed Crag) bed is to be found. 



Our views having been expressed as to the genuineness of the 

 Crag Mollusca, we now proceed to point out that which we consider 

 to be the true reading of the difficulties presented in working out 

 the Eed Crag in its various aspects. 



Having already suggested a re-distribution of the Crags, the area 

 occupied by each has now to be particularized. 



The Coralline (or Lower) Crag occupying its present area, we 

 propose allotting the other Crags thus:— The Middle Crag to consist 

 of the lower deposits commencing at Walton-on-the-Naze, and ex- 

 tending to Bentley on the west, thence running eastward to Butley 

 Abbey and Hollesley. 



