490 



PLEISTOCENE. 





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The sands also contain shells (see p. 492). Mr. 

 Mackintosh has observed that in the western part of 

 the plain of east Denbighshire and Shropshire the 

 Upper Boulder Clay degenerates into a loamy gravel, 

 which in many places covers the Middle Drift sand 

 and gravel, as around Whittington, Oswestry, etc. 

 The Upper Boulder Clay is well represented be- 

 tween Shrewsbury and Wellington. The Lower 

 Boulder Clay also degenerates south of Chester, 

 passing into gravelly and loamy deposits. 



In the Isle of Man Mr. J. Home has described the 

 following beds : — 



Boulder Clay, containing some scratched stones 

 and angular boulders, 6 to 8 feet. 



Sands and Gravels, finely stratified with many 

 foreign rocks, also Chalk-flint, evidently a 

 marine deposit, 8 to 10 feet. 



Bluish clay, very tough, containing scratched 

 stones, but no large boulders, about 12 feet 

 in thickness ; this is the representative of the 

 Scotch Till, and a product of land-ice. 



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The beds are well exposed about half a mile south 

 of Ramsey, and they are overlaid by a series of well- 

 stratified sands and gravels, which appear to rest on 

 an eroded surface of the boulder clay, and pass up- 

 wards into that great series of sands, gravels, and 

 shelly clays which form the cliff from Ramsey to the 

 Point of Ayre. The shelly clays contain marine 

 Mollusca. Some of the gravels belong to the Esker 

 series.^ Drift gravel with many granitic and other 

 boulders occurs on the Calf of Man. North of 

 Ramsey the sands are here and there cemented into 

 hard concretionary masses. 



Esker Drift occurs on the western slopes of the 

 Lancashire moorlands, from 200 to 400 feet above 

 the sea-level ; the constituents are more local than 

 those of the Middle Drift, and are not scratched. 

 Gravel knolls of an esker-like character have been 

 observed between Minera and Llangollen Vale ; and 

 also in Cheshire, at Delamere Forest, Newchurch 

 Common, and Ellesmere.^ The Meres of Delamere, 

 etc., occur in the Glacial sands. (See p. 241.) 



In North Wales there are many scattered Drifts, 

 and as remarked by Sir A. C. Ramsay these deposits 

 often rest on and sometimes conceal the rounded, 

 polished, grooved, and scratched surfaces [roc/ies 

 monloiinees), due to the operation of glaciers, the 

 effects of which are so clearly traceable in the Pass 



O u o 

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1 Trans. Edin. Geol. Soc ii. {1874) ; G. Mag. 

 1S75, p. 329 ; J. A. Birds, //'/(/. pp. 80, 226, 428 ; 

 J. C. Ward, G. Mag. 1S80, p. 6 ; J. G. Gumming, 

 Q. J. ii. 317, X. 211 ; H. E. Strickland, Proc. G. S. 

 iv. 9 ; H. H. Howorth, G. Mag. 1877, pp. 410, 456. 



2 Mackintosh, Q. J. xxxviii.' 184; G. Mag. 1877, 

 p. 94 ; A. Strahan, Geol. Cheshire, Iron and Steel 

 Inst. ; Geol. Chester (Geol. Surv.), p. 17. 



