PLIOCENE PEEIOD IN ENGLAND. 523 



were preceded by a complete emergence of this part of England. It 

 is therefore probable that before the formation of the Purple Clay- 

 ceased it became in Holderness altogether of terrestrial accumulation*, 

 and that the upper portion of it possesses the chalkless character, 

 because the "Wold to the north had, before the accumulation of this 

 later part, become covered with, and protected from degradation by, 

 a cushion of moraine which is itself chalkless by having come from 

 the area north of the Wold. 



Although from the destruction, denudation, and disturbance which 

 it has undergone, and its consequent connexion with the case to be 

 presented in the second part of this memoir, I defer all description 

 of the gravel shown in figure YI. by the letter / to that part, yet it 

 appears to me that as the rise had proceeded to the extent of some 

 70 feet only from the disappearance of the Chalky-Clay ice when this 

 gravel began to emerge, and the phenomena connected with the 

 recovery from the westerly depression in the Thames valley do not 

 become conspicuous until after this, the gravel / is most probably 

 synchronous with this latest and chalkless part of the Purple Clay, 

 and so of Glacial age. 



I have not attempted to show on Map 1 the Lower Boulder-clay 

 of the jSTorth-west. Lying west of the Pennine, that clay does not 

 appear to reach further south than Sheet 81, though it stretches 

 westwards from that sheet into North "Wales. This formation, as it 

 contains, like the Purple Clay, the shells and shell-fragments of 

 marine MoUusca mixed up with it, has, I consider, had its origin by 

 submarine extrusion, in a similar way ; but the species to which these 

 remains in the North-west belong are all of the Moel-Tryfaen 

 typef; and of the two extinct and one North- American species of 

 Bridlington not a trace has been detected. Seeing* that at the 

 commencement of Stage II. the sea was confined to the east, and 

 that neither the centre nor the west of England had become sub- 

 merged, it is entirely consistent with the case which I have been 

 presenting that these should be absent ; and the only question to 

 my mind besetting this part of the case is how far the clay of the 

 North-west, except any part of it which may be terrestrial^, is syn- 

 chronous with the Chalky or with the latest bed of Stage II., b S. 



When we see how all the earlier formed Chalky Clay and all 

 beds of Stage II. which lay in the path of the ice have been 

 destroyed, and reconstructed as new moraine, and carried outward in 



* I do not, however, regard the patches of mud with freshwater sheUs 

 described by Mr. Lamplugh in Greol. Mag. for September, 1879, as occurring 

 in the lower part of the Purple CLay at Bridlington as in any way connected 

 with land conditions where these occur. They are, in my opinion, of similar 

 origin to the patches in the pebbly sands of the Cromer Olilf on which Mr. 

 E/Cid has founded a division of those sands ; that is to say, they are scraps of 

 freshwater deposits brought by ice from other localities, just as was the sheet 

 of peat which in Stage 11. I found interbedded in 6 ^ at Cromer ; and the way 

 which Mr. Lamplugh describes these as tilted, cut up into shreds, and 

 separated from each other by thick walls of Boulder-clay containing marine 

 shells, one of them being, he observes, " to all intents and ^urjioses a boulder 

 itself" clearly shows this. 



t Eor list see Reade in Quart. Journ. Geol. Soc. vol. xxx. p. 27 ; Shone in vol. 

 xxxiv. p. 134. X As to which see p. 478 and bed b of fig. XVII. p. 490 . 



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