TF. Keejnng — Glacial Geology of Wales. 251 



Fig. 4. Chemnitzia lineata-procera, var. Scnrburgensis, Morris and Lycett. Scar- 

 borough Limestone. Leckenby Collection. 

 ,, 5. Chemnitzia vittata, Phil. Cornbrash, Scarborough. Leckenby Collection. 



a. Front view ; b. back view. 

 ,, 6. Ibid. Specimen showing an earlier stage. Cornbrash, Scarborough. 



Leckenby Collection. 

 ,, 7. Eulima laevigata, Morris and Lycett. (Type Eefigured.) Scarborough 



Limestone. Bean Collection, British Museum. 

 ,, %. Ibid. Variety from the Cornbrash, Scarborough. Leckenby Collection. 

 ,, 9. '^ Chemnitzia''^ vetusta^Vhil. Millepore Bed, Cloughton Wyke. Leckenby 



Collection. 

 ,, 10. Ibid. Specimen from same locality. Bean Collection, British Museum. 

 ,, 11. Ibid. Specimen from the Dogger, Blue Wyke. Leckenby Collection. 

 ,, 12. '■'■Chemnitzia" vetusta major. Dogger, Blue Wyke. Leckenby Collection. 

 ,, 13. '^Chemnitzia" vetusta, var. seminuda. Dogger, Blue Wyke. Leckenby 



Collection. 

 ,, 14. "■Chemnitzia" vetusta, var. "$ scalar if or mis, Deslong. Millepore Bed, 



Cloughton Wyke. Leckenby Collection. 

 ,, 1.5 and 16. Varieties of the vetusta-^vow^. 15 from Millepore Bed. 16 from 



Dogger (see p. 248). 

 ,, A. Body-whorl of a variety of 2Iehtuia scalar if or mis, from Bradford Abbas, to 



show the character of the aperture. 

 „ 17. Cf. Cerithium muricato-costatum, Miinst. Millepore Bed. Leckenby 



Collection. 



(To be continued.) 



II. — The Glacial Geology of Centkal Wales. 



By Walter Keeping, M.A., F.G.S. ; 



Keeper of the York Museum.^ 



IN Cardiganshire and the neighbouring counties of Central Wales 

 there are abundant traces of the action of the great accuinulations 

 of ice and snow which covered all the mountains of Britain in the 

 Glacial period. In the valleys lie thick sheets of Till and morainic 

 formations, the hill- sides are rounded and polished by the friction of 

 the moving ice, and erratic blocks are strewn in abundance over hill 

 and valley throughout the district. 



Geology and Physical Features. — The solid geology of the country 

 has been already described by me elsewhere,^ and it is only necessary 

 here to mention that the whole country consists of monotonous 

 repetitions of greywacke (hard argillaceous grit), hard shales, and 

 imperfect slates, the latter forming a large area by itself in the 

 central part 



The whole country is mountainous ; the hills are rounded and 

 bare, and the highest ground is usually a dreary level waste of wet 

 and boggy ground, dotted with lakes and pools. The two most 

 important physical features of the district are the great planes of 

 marine denudation which limit the height of the hills, truncating 

 their tops, so that a view from the summit shows a great plain, irregu- 

 larly broken up by the river valleys. The lower plane rises gradu- 

 ally from 400 — 500 feet at the coast to 700 feet inland, and the higher 

 plane starts abruptly at about 1100 or 1200 feet, and gradually 

 slopes up to 1500, where it abuts against the highest island-like 



1 Bead at the Meeting of the British Association, Section C, at York, 1881. 



2 Quart. Journ. Gaol. Soc. 1881, p. 141. 



