PLIOCENE PEEIOD IN ENGLAND. 521 



of the emergence in that part had by this time brought it, came 

 down between the Pennine and the western side of the Wold, as an 

 offset from that which, crossing Stainmoor, had previously issued 

 through the Tees valley and formed the eastern arm of the Purple 

 Clay. This western arm of the Purple-Clay moraine having been 

 brought by ice which terminated in the sea that entered the Lower- 

 Trent system as the ice of the Chalky Clay deserted this, it would 

 at its seaward extremity rest on or intermingle with the gravel e. 

 The eastern arm of the Purple -Clay ice terminated in the sea which 

 had covered the Basement Clay of Holderness from the time when, 

 in consequence of the changing inclination and increasing submer- 

 gence during Stage II., the land-ice had deserted this part to 

 issue seawards along the west of the Wold ; but it did not, I think, 

 come into existence as a separate body of ice, and reach Holderness 

 until after the Chalky Clay had made some progress. 



By the continued rise of the land during Stage III. the inter- 

 ception of the Atlantic vapours, in the form of snow, by the Pennine 

 and by the Westmoreland mountains increased, and with it the 

 volume of the land-ice. This, jQlowing from these mountains, at 

 length became more than could escape down the valleys of the Lune 

 and Eden, which were its only avenues between these mountains and 

 the Pennine, so that it rose above the level of the Pennine water 

 parting at Stainmoor (in south-east of Sheet 102) and flowed over it, 

 bringing with it the Shap blocks from the western slope. The ice 

 which produced the Chalky Clay, originating wholly on the Pennine 

 and flowing southwards between the Pennine and the Wold,received 

 no erratics from the western slope, such as the Shap blocks, 

 which this altered flow in mounting the watershed brought with it ; 

 but flowing down the eastern slope of the Pennine as far as its 

 southern extremity, and extending in the north higher than the sub- 

 mergence had done (though descending to a lower level towards 

 Sheet 63), it destroyed the gravels which during Stage II. had been 

 deposited on this side. The increase of the ice from the Westmore- 

 land mountains may alone have been the cause of this transit at 

 Stainmoor ; but as the ice of the Hessle Clay, which I shall exa- 

 mine in the second part of this memoir (and which I now think is 

 as much the moraine of land-ice as is the Chalky Clay, and not, as I 

 at one time supposed, a formation due to coast-ice), took quite a 

 different direction from that which the ice of the Chalky Clay did, and 

 sought the sea nearly in the position it occupies at the present day, 

 in consequence of the present inclination of the land having then 

 been attained, it is possible that the transit may, in some degree, 

 have been due to this recovery having begun with the Purple Clay. 



As the ice thus crossing the Pennine issued through the Tees 

 valley, it augmented the flow which had gone in that direction 

 during the earlier part of the Chalky Clay, so that this reached the 

 north-east of Lincolnshire, coming southwards with a westerly in- 

 clination, so as to cause it to hug the eastern side of the Chalk 

 wold. In the east of Yorkshire, below the level I have men- 

 tioned, at any rate, there was at this time the sea, and here the 

 morainic material became modified by its submarine extrusion ; so 



Q.J.G.S. JSro.144. 2n 



