S. V. Wood, Jun. — Sequence of Glacial Beds. 19 



- g. The Contorted Drift of Norfolk and its mnrl representative. Between 

 tills and h thnrn is a very ronspictious denudation and uncon- 

 Lowcr j fi)rmi(y visihlc 111 Ihi.shoro' did'; but, it soeins local, iiiid i.s very 



Glacial. i dill'erent in character and extent to the other unuonforniitics and 



denudations mentioned. 

 h. The Cromer Till and the Pebbly sand of Norfolk and Suffolk. 

 A marked unconformity and denudation here aj^ain occurs ; the interval of which 

 ii, as I now think, marked by the Cromer Forest and its associated fresh -water beds. 



(t. The Chillesford clay and sand, forming the upper or marine portion 

 of the Norwich Crag. 

 k. The Red Crag, and the lower or fluviomarine portion of the Norwich 

 Crag. 



In addition to the above may be added a class of mound-like 

 gravels in the mountainous parts of Britain, due to the action of the 

 Glaciers occupying the mountain valleys during the Post-glacial 

 period\ and which probably extend over the greater part (and, in the 

 higher latitudes of Britain, indeed of the whole) of the period 

 embraced by the deposits a to d inclusive, but to which I shall have 

 no occasion to allude in this paper. 



Subsequent to the latest of the above series (a) the land has 

 undergone a depression by which the forests occurring under the 

 coast silt and alluvium were buried; the greatest extent of this 

 depression of which we have evidence being that of 56 feet below 

 high-water mark at Grrimsby. 



The Gravel formation, extending from the neighbourhood of 

 Eeading to that of Canterbury, and of which a part occupies the 

 Thames valley between Pangbourne, in Berks., and Fobbing, in 

 Essex, is omitted from this table for the sake of simplicity, I regard 

 it and its associated beds with Cyrena Jluminalis as coeval with the 

 beds b and c. 



Between e and c there occurred the great emergence of the land 

 from the climax of the Glacial submergence — a submergence that 

 we know, from the dispersion of the Shap granite blocks, to have 

 amounted to 1,400 feet at the least. This emergence was accom- 

 panied by a very great denudation, that is feebly marked by the 

 beds d, forming, necessarily, the terms of a long series, of which the 

 highest are the oldest, and the lowest the newest ; all those occurring 

 in East Anglia, where the highest elevation does not exceed 550 feet, 

 belonging to the latter class. It was not nntil the emergence 

 had reached a point corresponding nearly to the existing level that 

 the beds c were formed, because we find in them at Kelsea the river- 

 shell Cyrena fiuminalis associated with a littoral marine fauna, which 

 proves that low-lying Holdemess had, at this time, become in close 

 contiguity to land. The re-submergence giving rise to the clay b, 

 which overlies c, was not only insignificant in amount when com- 

 pared with that great submergence in which the Glacial period 

 culminated, but was also local in its extent ; the general lay of the 

 clay b indicating that its maximum submergence — which could 

 scarcely have exceeded 350 or 400 feet anywhere in Yorkshire, if 

 indeed it amounted to so much — died off to nothing towards southern 



1 Different altogether to tlie enveloping Glacier, or ice sheet of the Glacial, or 

 •ubsidence period referred to in the latter part of this paper. 



