32 GEOLOGY. 



surrounded by valleys, which generally run N.E. and S.W. The Menai 

 Straits occupy such a valley. The glacial striae of this low land gene- 

 rally run from about 30° to 40° W. of S., or nearly parallel with the 

 valleys, all of which have been worn in comparatively soft rocks. The 

 author infers that these valleys had been mainly hollowed by an ice- 

 sheet coming from the Lake District, large enough to prevent the local 

 glaciers of the Snowdon range from intruding upon the low grounds of 

 Anglesey. In this manner the valley of the Menai Straits was exca- 

 vated. After emergence it was probably filled by Boulder Clay, which 

 has been gradually worn away by marine waste and subaerial drainage; 

 and thus Anglesey has become separated from the mainland. W. T. 



Ramsay, Prof. A. C. On the Physical History of the Dee, Wales. 

 Quart. Journ. Geol. JSoc. vol. xxxii. pp. 219-229 ; folding section. 



From Erbistock to its mouth the Dee flows in a pre-glacial valley ; 

 evidence is given that the same is true of the Dee above Erbistock. 

 Bala Lake lies in a rock-basin ; it is now 3J miles long, but has ex- 

 tended for 8 miles. Evidence is given of the vast area once covered 

 wdth Carboniferous rocks, which spread over a plain of marine denuda- 

 dation formed of Silurian rocks. The region was disturbed and elevated 

 before and during the deposition of the Permian beds, from which 

 time until the Glacial period it has probably been dry land, except 

 possibly during the deposition of the Chalk. During this long time 

 the valleys were being excavated by subaerial action. In the Glacial 

 period the valleys were modified in shape, and the lake-basins ex- 

 cavated. The main features of the country are thus preglacial ; the sub- 

 mergence during part of the Glacial period, and subaerial waste since that 

 period, have done but little in altering the shape of the land. W. T, 



Reade, T. M. The Lower Lias of Street, Somerset. Proc. Liverpool 



Geol. Soc. vol. iii. part ii. pp. 97-99. 

 Describes a railway-cutting in the Rhaetic Beds between Midsumer 

 Norton and Shipton Mallet, and the L. Lias quarries of Street. 



. . The Formby and Leasowe Marine Beds, as shown in a section 



near Freshfield. Proc. Liverjjool Geol. Soc. vol. iii. part ii. pp. 120- 

 122. 

 Excavations at North Moss Lane, 30 feet in depth, prove blue clays 

 with Scrohuularue, &c. beneath 8 feet of peat. 



Pebble Ridges. Geol. Mag. dec. ii. vol. iii. pp. 360, 361. 



Describes a small beach just W. of the Bryn Ddu Limestone- 

 quarries, Auglesea. The stones and boulders come from the W. ; but 

 at the W. end the stones are small ; the large ones are carried to the 

 E. end, and are there piled up in a ridge. The author applies the 

 facts here observed to explain the formation of the Chesil Bank (see 

 Geological Recoed for 1874, p. 32). W. T. 



