Mr, Godwin- Austen's Address. 477 



Seaiics Wood states, "the Norwich Crag is not geologically distinct 

 from the lied, but a fluvio-marine condition of the same period." 

 He establishes this in an analysis of the molluscan fauna, such as 

 leaves little doubt as to this point ; and the only criticism which is 

 suggested is — may it not have been an equivalent of the whole Crag 

 period ? and may not the Yar valley have been a tributary to the 

 Crag Sea, during its whole duration as such ? 



In Suffolk, the fluvio-marine accumulations at Thorpe, near Aid- 

 borough, Wangford, and Bulchamp, are considered by Mr. S. Wood 

 to be of the same age as that of Norwich. 



The Forest-hed of Cromer (182-i), and some other places, to which 

 Mr. K. C. Taylor first called attention, and to which he assigned its 

 true age and position, is one of the most interesting points in Norfolk 

 geology ; it is the unmistakeable indication of a terrestrial surface, 

 antecedent to the period of the " Glacial Drift" accumulations. This 

 old land-surface, at Cromer, is exposed at the sea-level ; but it ex- 

 tends inland, and has been met with at considerable depths in the 

 offing. 



The arboreal vegetation buried in these beds comprises the Norway 

 spruce, Scotch fir, yew, oak, alder, — all of them common North- 

 European trees. 



What the Cromer coast-section demonstrates is, that by process of 

 change of level a forestial condition of the surface had been brought 

 down to the sea-margin, that the trees had died, and that mud-de- 

 posits had formed, partly under fresh, partly under brackish water 

 lagoons. 



Subjacent to the '' Forest-bed," and covering the surface of the 

 Chalk, is a layer of chalk-flints ; a like accumulation is seen resting 

 on the Chalk in numerous other places, as in the sections below this 

 city (Holy Cross, Thorpe, &c.), and are all referable to the same 

 agency and period. The Chalk has been dissolved away by the 

 action of rain-water, and the flints left in situ ; they indicate a long 

 period of subaerial conditions, and their formation is co-extensive 

 with the whole duration of those conditions ; they are therefore of 

 the same period as the '' Forest-bed." All collectors and observers 

 seem now to be agreed upon this, that the Cromer mammalian re- 

 mains are referable to this particular surface. 



B. Glacial. — More recently the Norwich sections have been sub- 

 jected to a closer examination ; and according to Mr. J. E. Taylor 

 (1867) these admit of a twofold division : the upper is a coarse and 

 rubbly accumulation, with well-rounded pebbles of flint ; the lower 

 consists of finer sands. A band of white cross-bedded sand inter- 

 venes. Such a change in the character of successive beds would not, 

 by itself, have been of much importance ; but zoologically the diffe- 

 rences they present are much more significant. 



The fresh and brackish-water forms, which long since gave the 

 Norwich Crag its fluvio-marine character, occur only in the lower 

 division; in this, too, the proportion of littoral species of marine 

 shells is greater ; and here also are found all those forms which are 

 supposed to be extinct. 



