THE GEOLOGY OF PUFFIN ISLAND. 93 © 
modifications can only be accepted with caution, and 
advanced with the deference due to the geologists opposed 
to them. But if the supposed submergence be abandoned, 
a great step will have been taken in the simplification of 
the interpretation and correlation of our glacial deposits, 
though they may yet be more complicated than Professor 
Lewis admits. If so, the lower boulder clay of North 
Wales, the Arenig drift of Professor Hughes, formed at 
the period of most intense cold, may have been syn- 
chronous with the deposition of the Bridlington beds; as 
Professor Hughes suggests,* a conclusion that thoroughly 
harmonizes with Mr. Mellard Reade’s contention,+ that 
the east coast was submerged before the west, and that 
before the latter was effected the most severe conditions 
had passed away. 
Of the age succeeding the glacial epoch, as far as Puffin 
Island is concerned, we know but little. Man then settled 
in the district, if he had not done so before, as Dr. Hicks 
would have us believe. I know of no trace of man’s 
presence on the island older than the church, which 
tradition says was built before the connection with 
Anglesey was severed, and though I have not met with 
any historical records on the subject, it is not improbable 
that such was the case. The Sound runs along a slight 
synclinal axis, and this depression may have guided and 
assisted the denuding agents ; the limestone was probably 
removed during the glacial period, and the strait filled up 
with detritus which would be easily removed. The main 
current through the Menai Straits would then flow through 
it, and the sands, washed from the glacial deposits that 
had choked up the straits, would be deposited in the quiet 
water under Penmaenmawr, and thus would have been 
* Quar. Jour. Geol. Soc., vol. xliii., pp. 78 and 88. 
t Proc. Livy. Geol. Soc., vol. iii. (1874-75), p. 43. 
