148 Correspondence— Mr, S. V. Wood, Jun. 



The accuracy and bearing of our respective sections I leave to the 

 judgment of others. 



From Mr. Green's view, that the Glacial and Post-glacial beds 

 cannot be represented on the inch scale without detriment to the 

 delineation of the older geology, I strongly dissent, so far as concerns 

 the secondary and tertiary area, south of Flamborough Head; and 

 I have done my best, in sheets 1 and 2, to show that all beds 

 may be represented together without detriment to any; and I 

 contend that it is beyond human ability to represent, with any 

 approach to accuracy, the geological features of such part of that 

 area as is occupied by the Glacial beds in force, except those beds 

 be mapped in with the older formations. North of Flamborough 

 Head it is otherwise. I have examined railways in course of 

 formation in Northamptonshire and Huntingdonshire, through 

 districts in which the hills and valleys appear from the survey 

 maps to be cut out of the secondaries, and in one instance out of 

 a succession of secondary strata ; but the cuttings have disclosed that 

 the hills traversed by them are wholly formed of the Glacial beds, 

 nothing of the map delineation being visible. 



Mr. Fisher has correctly represented my views as to the cappings 

 termed Trail; and I quite agree with him that the Clacton and 

 Grays deposits are of similar age, having so expressed myself at 

 page 350 of your third volume. The other points in his letter 

 would take up too much of your space to discuss ; but, if the in- 

 formation he obtained from the Witham boring be truly reliable, 

 it seems to point to a great local disturbance and denudation of the 

 four or five miles from Kelvedon to Witham, either between the 

 Middle and Upper Glacial formations, or during the earlier part of 

 the Upper; and I suspect that in such case my sections, No. 9 of 

 page 348 of your third volume, and No. 9 of page 402 of the twenty- 

 third volume of the Quart. Journ. of the Geol. Soc, may prove to 

 contain an error in so far as they show the Middle Glacial dipping 

 with a fold under the Upper, where they cross the Blackwater. 

 There is, I think, evidence, from clear sections, of such an inter- 

 mediate disturbance and denudation near Ipswich, the effect of 

 which has been to bring the Glacial clay into the bottom of the 

 Gipping valley for three or four miles without any Middle Glacial 

 under it ; while the Middle and Upper Glacial beds form the whole 

 country around, the valleys being entirely cut out of them. The 

 Gipping valley, except where this anomalous structure occurs, forms 

 no exception to the general features presented by these valleys, and 

 the case of the Blackwater seems much the same. I am very glad, 

 although I dissent from the gravels over the Hampshire Tertiaries 

 being the equivalent of the Glacial clay, to see Mr. Fisher dis]30sed 

 to regard the Glacial sea as having extended over the South of 

 England prior to the great upheavals and denudation of that part, 

 and to connect the dislocations in the Thames valley with those 

 movements ; these being the most important links in the chain of 

 events which I contend have followed the Glacial period. 



S. V. Wood, Jun. 



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