492 PLEISTOCENE. 



The following Mollusca are most abundant : Tellina Balthica, Cyprina Islandica, 

 Cardhim ediile, Astarte borealis, A. compressa, Turritella terebra, Trophon 

 aiitiqiiHs, etc. Over 60 species have been obtained at Moel Tryfaen, and of these 

 II species are arctic or northern forms, most of them are littoral, and the rest 

 indicate depths of from 10 to 20 fathoms.^ It has been suggested that the beds 

 were not originally deposited where they are now found, but were thrust uphill by 

 an advancing ice-sheet.- It has been argued on the one hand that the forms of 

 Mollusca would not have lived together, and on the other, that ice would have 

 crushed the delicate shells ; but nearly all the organisms are more or less 

 fragmentary, although perfect specimens of Tdlina Balthica have been obtained. 

 Moreover, as Trimmer observed, beneath these Drift deposits the surface of the 

 slate-rock is " covered with scratches, furrows, and dressings." 



Sands and gravels containing marine shells, were discovered by Prof. Prestwich 

 at the height of 1200 feet east of Macclesfield in Cheshire. The beds are about 

 35 feet thick, and the shells include Cytherea c/iioiie, Area lactea, Tellina Balthica, 

 Cyp) ina Islandica, Carditim rustieitin, C. editle, Astarte arctica, Turritella terebra, 

 etc.'^ The first two species are southern forms, and the other species indicate 

 temperate con<litions. North of Macclesfield, shells have been found in sand and 

 gravel at the new cemetery, at heights of 500 feet and upwards. The thickness of 

 the beds is in places 100 feet, and at Congleton they are overlaid by Boulder Clay. 



Shells have been found at Upton and near Tarporley in Cheshire,'* at Preston 

 (350 feet high),^ Leylands (Worden Hall Pits), and Blackpool in Lancashire. 

 The sands at Blackpool Cliff, etc., have yielded Nassa reticulata, Biiccinum 

 undatum, Aporrhais pes-pelicani, Fin-piira lapillus, Litiorina littorea, Astarte 

 borealts, Carditwi ediile, Tellina Balthica, Ostrea edidis, Mytilus ediilis, etc. 

 Shells have also been found in the Drift at Petton in Shropshire, near Crewe, at 

 Lilleshall Abbey, north of Shiffnall, and at Strethill, near Buildwas station, and 

 other places in the Severn Valley between Bridgnorth and Shrewsbury.^ In 

 Shropshire these shell-bearing sands and gravels are about 30 feet thick, and 

 rest on blue (Boulder) clay. At Ironbridge the thickness of the Drift is upwards 

 of 200 feet. 



From the occurrence of marine shells in the sands and gravels of Shropshire, 

 Staffordshire, and Worcestershire, Murchison and Prof. Buckman were led to 

 infer an ' Ancient Strait of Malvern,' and that the sea had covered the Valley of 

 the Severn from Bridgnorth to the Bristol Channel. It is quite likely that this 

 was the case, but a large area of the midland and eastern counties was at the same 

 time submerged.' 



The " Weaver Clays " of the Weaver Hills, north-east of Cheadle, in Stafford- 

 shire, described by Mr. Edwin Brown, consist of white clays and sands roughly 

 bedded, 30 feet thick at Ribden. The former beds furnish fire-clay, and the sands 

 are used for glass-making.** The beds are overlaid in places by Boulder Clay, and 

 they are occasionally much disturbed : their age is, however, extremely doubtful. 

 (See p. 444.) 



1 J. Gwyn Jeffreys, Q- J. xxxvi. 353. 



2 T. Belt, Nature, May 14, 1874"; C. Reid, G. Mag. 1881, p. 235. See also 

 H. H. Howorth, G. Mag. 1883, pp. 9, 71, 113; and J. G. Goodchild, G. Mag. 

 1874, p. 496. 



3 R. D. Darbishire, G. Mag. 1865, p. 293; Mem. Lit. and Phil. Soc. 

 Manchester (1864), iv. 41 ; Q. J. xxx. 38 ; W. Shone, Q. J. xxxiv. 383 ; E. Hull 

 and A. H. Green, Geol. Stockport, etc. pp. 77, 95 ; T. M. Reade, Q. J. xxx. 27, 

 xxxix. 83, 95. 



* Egerton, Proc. G. S. ii. 189 ; De Ranee, P. Geol. Assoc, iv. 229. 



* J. Rofe, P. Geol. Assoc, i. 321. 



« Miss C. Eyton, G. Mag. 1870, pp. 106, 545 ; J. E. Taylor, Ibid. p. 162 ; 

 E. W. Binney, Ibtd. 1S67, p. 231 ; G. Maw, Q. J. xx. 130, G. Mag. 1867, p. 279; 

 C. J. Woodward, G. Mag. 1865, p. 567 ; Geol. and Nat. Hist. Repertory, i. 157 ; 

 Trimmer, Proc. G. S. ii. 200. 



'' Murchison, Proc. G. S. ii. 231, 334 ; The Ancient Straits of Malvern, by 

 J. Buckman, [n.D.]. 



8 G. Mag. 1867, pp. 248, 335, 382. 



