546 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 20, 



as this may not improbably belong to the horizon of the Fluvio- 

 marine Crag itself, or at least of the sand intervening between that 

 Crag and the Chillesford beds, I append them separately, viz. : — 



Pecten opercularis. Circe minima. 



Pinna. Donax trunculus. 



Nucula nucleus. Saxicava rugosa. 



Leda myalis. Clavatula turricula. 



Diplodonta rotundata. Caneellaria costellifera. 



Venus ovata. Scalaria Groenlandica. 



Tapes perovalis (?). Eingicula buccinea. 



The foregoing list from Toft Monks is entirely on the authority of 

 Mr. Eose ; the others are upon my own, unless where otherwise 

 expressed. 



With respect to the false-bedded and horizontal or water-depo- 

 sited Crag, which seems to occur in channels cut through the obhque 

 or Beach Crag of Sutton, and at the base of which only the Coprolite- 

 beds occur, it is difficult to bring it into a satisfactory correlation 

 with any of the other horizons to which I have alluded. The bed 

 is composed of such degraded materials, being in the upper part 

 almost entirely comminuted, that one cannot resist the inference 

 that it has been derived, in great measure, from the destruction 

 and redeposit of the material of the oblique Crag which surrounds 

 it. Erom this circumstance, its fauna cannot be satisfactorily arrived 

 at, as the greater portion may be, and probably is, derivative; 

 added to which, the existence of the phosphatic nodule-band, with 

 its miscellaneous assemblage of fossils of various ages, marks it as 

 something altogether distinct from the beds of the Red Crag in 

 contact with it. I have myself verified the fact which has been 

 pointed out, that angular and apparently ice-borne chalk-flints 

 occur in it ; and this circumstance would certainly seem to point to 

 its age being rather that of those upper horizons which I have 

 described, in which the northern forms prevail, and where ice- 

 transport came into action, than that of the surrounding oblique- 

 bedded Crag of Sutton, in which so large a proportion of the more 

 southern types that are peculiarly the characteristic of the "Walton 

 Crag are intermingled : and it may be, as my son supposes, that the 

 lower part of this Crag is the water-deposited equivalent of the 

 highly-beached and oblique Crag of Butley and Chillesford, and the 

 upper that of the Scrobicularia-Crag. Certain it is that, unlike the 

 oblique Crag, which everywhere presents a rugged surface to the red 

 sands which overlie it, this phosphatic nodule-crag passes up into 

 those sands by interbedding. 



EXPLANATION OF THE DIAGEAM SECTION. 



By S. V. Wood, Jun., Esq., F.G.S. 



The line of section starts north from a point about 6 miles south-west of 

 Chelmsford, and proceeds through Chelmsford and Witham to Colchester; 

 then turning east, reaches the sea near Walton Naze. It proceeds thence to 

 near Woodbridge, whence it turns north-east, and reaches the coast again at 

 Aldborough, which it follows as far as Pakefield, whence, turning north-west, 

 it is carried through Beccles, Rockland, Bramerton, Brundall, and Thorpe, to 

 Norwich. Proceeding thence in a northerly direction through Wroxham, 

 Coltishall, and North Walsham, it reaches the coast again at Hasborough, and 



