Geological Society of London. ol 



Geological Society of London. — November 20th, 1807. 

 Warington W. Smyth, Esq., M.A., F.E.S., President, in the Chair. 

 The following commimications were read : — 1. " On the Glacial 

 and Post- Glacial Structure of Lincolnshire and South-east York- 

 shire." By S. Y. Wood, Jun., Esq., F.G.S., and the Rev. J. L. 

 Rome, F.G.S. The features of Yorkshire and North-east Lin- 

 colnshire, having distinctive characters from those of Central and 

 South Lincolnshire, the authors described the two areas separately. 

 In the former, their coast sections exhibited the Glacial clay sepa- 

 rated into two portions ; of these the lower, which they identified 

 with the ordinary (or ujDper) Glacial clay of the south, contains 

 abundant chalk debris ; but the upper or purple portion (which 

 was in j^laces divided from the lower by sand or gravel beds) 

 contains no Chalk in the upper, and but little in the lower part 

 of it, the place of the Chalk being taken by swarms of Paleo- 

 zoic fragments. The latter of these clays alone extends over tlie 

 Wold-top at Speeton, and alone occupies the valley along the 

 northern Wold-foot, and so away northwards to Scarborough, and 

 the Tees' mouth, from which the authors infeiTcd that the north of 

 England did not subside beneath the Glacial sea until after the 

 south had been submerged. The so-called Bridlington " Crag " 

 was shown to be an intercalated bed in this purple clay. Both 

 these clays were shown to be denuded, and their denuded edges to 

 be everywhere covered by a much thinner Boulder-clay, that of 

 Hessle, which wraps Holderness like a cloth, extending to altitudes 

 of 150 feet, and running down the east of Lincolnshire to the Fen- 

 border. This Post-glacial Boulder-clay of Hessle is again cut 

 through, and in those places covered by posterior beds of gravel, 

 one of which (at Hornsea) contained fluviatile shells. At Hull this 

 clay supports a forest, which is now submerged 33 feet below the 

 Humber; the same submerged forest also occurring at Grimsby. 

 The authors regarded the position of the sea during the Post-glacial 

 period as having been principally on the west of the Yorkshire and 

 North Lincolnshire Wold until the formation of the gravel-troughs, 

 cutting through the Hessle clay, and that its present position was 

 connected with a recent westerly elevation and easterly depression. 



The Glacial clay of central and South Lincolnshire belongs to the 

 chalky portion, from which all the superior or purple part of the 

 formation has been denuded ; and the valleys of Central Lincoln- 

 shire were shown to be cut out of the Cretaceous series and Glacial 

 clay as a common bed, the hills formed of the clay rising to eleva- 

 tions equal to the Wold in that part. 



The Glacial clay of both areas was shown to be denuded west- 

 wards ; and the denuded edges occupied with sands and gravels, 

 termed by the authors denudation-beds. 



2. " On supposed Glacial markings in the Yalley of the Exe, 

 North Devon." By N. Whitley, Esq. 



