1867.] ■VVHITLEY SUrrOSED GLACIAL MARKINGS. 3 



coast-sections exhibit the Glacial clay separated into two portions : 

 of these the lower, which they identify mth the ordinary (or upper) 

 Glacial clay of the South, contains abundant chalk debris ; but the 

 upper or purple portion (which was in places divided from the 

 lower by sand and 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 fragments &f Palaeozoic rocks. The latter of these clays 

 alone extends over the 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 infer 

 that the north of England did not subside beneath the glacial sea 

 until after the south had been submerged. The so-called Bridling- 

 ton " Crag " is shown to be an intercalated bed in this purple clay. 

 Both these clays are 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 Postglacial Boulder-clay of Hessle is again 

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

 one of which (at Hornsea) contains 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 regard the position of the sea during the Postglacial 

 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 Lincolnshire 

 are shown to be cut out of the Cretaceous series and Glacial clay as 

 a common bed, the hills formed of the clay rising to elevations equal 

 to the Wold in that part. 



The Glacial clay of both areas is shown to be denuded westwards, 

 and the denuded edges occupied with sands and gravels termed by 

 the authors denudation-beds. 



2. On Supposed Glacial Markings in the Valley of the Exe, 

 North Devon. By N. Whitley, Esq. 



(Communicated by the Assistant-Secretary.) 



In a late paper on the grouping of the rocks of North Devon, 

 Professor Jukes mentions some glacial grooves observed by him in 

 the valley of the Exe. The interest attached to this subject in 

 such a country induced me to visit the spot ; and in driving down 

 the valley I found the " grooved " rocks about half a mile above 

 Barlynch Abbey, and on the north face of a projecting tongue of 

 hard purple grits. Two separate portions of the rock were deeply 

 indented ; and the long straight furrows, like a bold cornice of a 



E 2 



