BRTFT8 OF THE VALE OF CLWYB. 



89 



and gravels of St. Asaph. These were originally determined for me 

 by Searles Wood. The collection is now in the Woodwardian Museum 

 at Cambridge. See also : — 



Hughes. " On the Evidence of the Later Movements of Elevation 

 and Depression in the British Isles,*' Yict. Inst, or Phil. Soc. 

 Great Brit., March 15, 1880, p. 6. 

 Hughes. " Notes on the Geology of the Yale of Clwyd,' ' Proc. 



Chester Soc. Nat. Sci. pt. 3, 1884, p. 29. 

 In column II. I have given an unpublished list, kindly placed at 

 my disposal by Mr. A. 0. "Walker, of shells collected and determined 

 by him from beds about 120-150 feet above the level of the sea in 

 Colwyn Bay. These specimens are in the Grosvenor Museum, 

 Chester. 



In column III. I have recorded the shells from MoelTryf an noticed 

 by :— 



Trimmer. Proc. Geol Soc. vol. i. 1831, p. 332 ; Journ. Geol. 



Soc. Dublin, vol. i. 1838, pp. 286, 335 : Kept.- Brit. Assoc. 



1838, Trans. Sect. p. 86. 

 Forbes. Mem. Geol. Survey, vol. i. 1846, p. 336. 

 Darbishire. Geol. Mag. vol. ii. 1865, Table, p. 298. 

 Mellarb Peabe. Quart. Journ. Geol. Soc. vol. xxx. 1874, p. 30. 

 Ramsay and Ethertbge. ' Physical Geography and Geology of 



Great Britain,' 1876. 

 Lyell. ' Antiquity of Man,' 3rd edition, p. 525. 

 Shone. Quart. Journ. Geol. Soc. vol. xxxiv. p. 383. 

 Gwrar Jeffreys. Quart. Journ. Geol. Soc. vol. xxxvi. 1880, 



p. 351. 



Gwyn Jeffreys says that the Moel Tryfan deposit was not strictly a 

 glacial one. The faima has a Norwegian rather than an Arctic facies. 



In column IY. I have placed the few shells which have been re- 

 corded from the sands and gravels which occur at intervals along 

 the high ground that rises from the Cheshire plain on the west, from 

 the Yale of Llangollen to the estuary of the Dee, thus forming the 

 eastern boundary of the Yale of Clwyd. I have verified the occurrence 

 of these by finding some myself, but I have not added to the species 

 recorded by Mr. Mackintosh *. 



In column Y. I have placed together all the recorded shells from 

 the drifts of the lower levels of Lancashire and Cheshire. Eor the 

 subdivisions of these beds the paper by Mr. Shone (Quart. Journ. 

 Geol. Soc. vol. xxxiv. 1878, p. 383) may be referred to. Mr. Shone 

 thinks that the lower beds of his sections are of considerably greater 

 antiquity, and indicate much more boreal conditions than the over- 

 lying sands and gravels and their covering clay. He suggests that 

 some of the northern shells found in the upper deposits may have 

 been washed out of older beds, and therefore not be a fair index of the 

 elimatal conditions of the deposit in which they are found. Mellard 

 Peade considers that the various beds from which he has obtained 

 shells in Lancashire and Cheshire are only local developments of one 

 series. Provisionally he groups them all together under the title of 



* Quart. Journ. Geol. Soc. vol. xxx. (1874), p. 712, vol. sxxvii. (1881), p. 360, 



