22 THIRD SUPPLEMENT TO THE CRAG MOLLUSCA. 



also requires the substitution of this colour for that of the Middle Glacial over most of the 

 area east of the chalky clay, which stretches from Sizewell to the River Blyth, and to the 

 cliffs of Easton Bavent and Covehithe ; there being but very little, if any, of the Middle 

 Glacial present over this area, which is occupied by the sand and shingle No. G in greater 

 thickness than elsewhere. 



The Section (h) of Dunwich Cliff, and that (s) of Easton Bavent and Covehithe 

 Cliffs, also require correction, the bed shown in the latter as the Contorted Drift (No 7) 

 being the same as the capping loam of Dunwich Cliff, which in Section r is shown under 

 the number 10;^ both of them being, as a late examination of them has enabled me to 

 perceive, a morainic bed formed (in Dunwich and the southern part of Easton Cliffs, 

 from a reconstruction of the pebbly sand No. 6 with some admixture of the material of 

 the chalky clay, and in the northern part of Easton Cliff, from a reconstruction of these 

 sands and the Chillesford clay together,) by the ice in its passage to the sea after this 

 part of Suffolk had emerged towards the close of the chalky clay formation ; and the gravel, 

 shown by the number 10, as resting on this bed and on the Chillesford clay in this cliff, and 

 shown also in Covehithe Cliff, is merely a part of this morainic bed, being pots of pebbles 

 derived from No. 6. A bed of this morainic material cutting like a dyke through the 

 sands No. 6 at the southern end of Easton Cliff (where this cliff is only six or seven 

 feet high) requires to be added to Section s. Another such bed forms the northern 

 extremity of Southwold Cliff, overlying the bed of derivative shells in the shingly sand 

 No. 6, presently to be referred to. The section of Dunwich Cliff also requires correction 

 by the omission of the Middle Glacial which is shown in it under the numbers 8", 8'", and 

 S"" ; all of this being part of the sand No. 6, to which the shingle under the ruins 

 (shown in Section r by the figure 10) also belongs ; and this shingle is still more largely 

 present in that sand at the southern end of this cliff. The whole of Dunw'ich Cliff, from 

 below the beach hne up to the capping loam of morainic origin just mentioned, is thus 

 formed of No. 6, the intercalation of clay shown in Section r by the figure 9 being 

 probably a modification of the sandy formation, by the introduction of argillaceous 

 material analogous to that which gave rise to the Cromer Till and Contorted Drift of 

 North Norfolk ; both of which are, in my view, merely modifications of the same shingly 

 sand by the introduction of a different sediment. 



Descending thus below the beach hne, and forming (with the morainic loam already 

 mentioned) the whole of the cliffs of Dunwich and Southwold^ this sand there occupies a 

 space from which the Chillesford clay and the upper part of the Crag beneath it had been 

 removed, so as to form a channel in the Lower Glacial sea which divided two islands 

 formed of Chillesford clay and Crag beds ; of which islands the southern was comprised 

 by the country extending from Butley and Chillesford to Sizewell, and the northern by 

 the area of which the cliffs of Easton and Covehithe (Sect, s) furnish a section. The 

 sands No. 6, which, as already mentioned, cover the Red Crag area, lie up to the 

 ^ See the footnote No. 5 to p. 29 of the " Introduction." 



