4O2 G lactation of ' Angle sea. 



Like Greenland of the present day, but on a smaller 

 scale, the whole of this basin of more than 120 miles 

 in diameter was deeply buried in snow and ice, which, 

 in glacier fashion, found vents through the broad gaps 

 in the circling mountains, westward into the Atlantic, 

 and eastward in the direction of what is now the Irish 

 Sea, to join the ice-sheet that worked its way south 

 from Scotland and the north of England. 1 



If all this be true, it is easy to see how any older 

 ice-grooves in Anglesea must have been obliterated, and 

 in aid of this argument I will now give a more par- 

 ticular account of the glaciation of Anglesea, seeing 

 that it has an important bearing on the whole question 

 of the great northern glacier. 



The structure of the low ground of Caernarvonshire, 

 within three or four miles of the Menai Straits, in 

 almost all respects resembles that of Anglesea, both in 

 its geology and physical geography. The Menai Straits 



1 With Messrs. Hicks, Homfray, and Etheridge, near St. David's, 

 on the coast of Pembrokeshire, I have seen well marked glacial 

 striations on the rocks on the coast at Trwyn-hwrddyn, Porth-clais, 

 and Pen-dal-deryn. In the first two they point NW. and SE., and 

 in the last NE. and SW. Boulder-clay with ice-scratched stones 

 is common, and chalk flints mingled with stones native to the 

 district, are not uncommon on the mainland and in Ramsey Island. 

 Flints are also found in quantity, mingled with ice-scratched 

 erratics, all along the low ground of Glamorganshire north of 

 Bristol Channel between Cardiff and Bridgend, and Boulder-clay is 

 indeed common here and there all over South Wales. When the 

 Geological Survey was in that district glacial phenomena had just 

 begun to be heard of, and the 'drift,' as it was termed, was chiefly 

 looked upon as a troublesome superficial deposit that concealed the 

 boundary lines of the solid rocks beneath. Till some qualified 

 person surveys the whole of the glacial phenomena of South Wales 

 and the adjacent counties in a connected manner, it would be pre- 

 mature to connect the striations in Pembrokeshire with the 

 northern glacier described in this book. 



