S. V. Wood, Jun. — Sequence of Glacial Beds. 21 



tlie Till, along the Cromer coast, and yielding similar shells, is 

 regarded by Mr. Harmer and myself, from the way in which the 

 Till disappears southwards towards Norwich, as the sands thicken, 

 and from other circumstances, as representing not merely the sand 

 underlying and interbedded with the base of the Till along the coast, 

 but also the Till itself, which contains sheets of chalk, stripped by 

 land-ice from the old Norfolk floor. Such shells and fragments as 

 the Till and the Contorted drift, g (which overlies the Till where 

 that is present, and, where it is not, overlies the pebbly sands), have 

 yielded, are all forms which occur in the Belaugh and Eackheath 

 sands ; and we feel no hesitation whatever in regarding the fauna 

 obtained from the sands at these localities, and at Weyboume and 

 Eunton, as being that which lived during the accumulation of the 

 beds g and h, forming the Lower Glacial of the above table. Now, 

 with the exception of Tellina Balthica [solidula), the test shell of the 

 Glacial and Post-glacial series, and of a new species of the fresh- 

 water shell Paludina, all the forms thus obtained belong to the 

 Upper Crag. 



The Middle Glacial shells now obtained by me, with the assistance 

 of Mr. Dowson (of Geldeston), from Hopton Cliff, where this deposit 

 actually occurs between g and e" — supplemented by some others 

 from the Bradwell Cutting, two miles inland of the cliff, where the 

 deposit is also capped by e", obtained by Mr. Eose, and identified for 

 him by Mr. Jeffreys —amount in number to thirty. These also, with 

 the sole exception of Tellina Balthica, are Upper Crag shells ; nine- 

 teen of them also occur in the pebbly sands \h). 



So far, therefore, as the evidence yet obtained goes, not a single 

 marine mollusc, with the exception of Tellina Balthica, had, from 

 the period of the Upper Crag down to the close of the Middle Glacial 

 formation, established itself in the East of England, though a number 

 seem to have disappeared. 



Throughout this time, and also throughout the formation of the 

 bed e", the most extensive of the series, the material of which the 

 beds are formed proves that the Chalk was the largest — indeed, in 

 many places, the almost exclusive — contributor, by its icy degrada- 

 tion, to their formation. 



At Bridlington, however, just at the horizon (e'), in the series 

 where the supply of Chalk debris begins to fall off, and when, we 

 may infer, most of the Chalk itself had, by the progress of the 

 submergence, passed out of the reach of the icy degradation, we get 

 a very marked and different fauna — different not only in the fact of 

 its containing many shells not known to the Crag, but in the circum- 

 stance that all of these introductions are of an Arctic character. Out 

 of sixty-seven Bridlington forms there are, inclusive of Tellina 

 Balthica, twenty-two not known to the Upper Crag ; the greater 

 part of these being exclusively arctic forms, and the rest (with the 

 exception of two, or perhaps three, not known Kving) British shells^ 

 extending, with one exception, into the truly Arctic seas. 



Throughout all the series up to this point, the now extinct shell, 

 Tellina obliqua, lived. In the Coralline Crag it occurs. In the Eed 



