^ and on Boulders transported by Floating Tee. 357 



however, a rather smooth pap of greenstone marked with a 

 few deep scores. 



The till forms, at the height probably of 600 feet above the 

 sea, a little plain, sloping seaward ; and between Bethesda 

 and Bangor there are other gently inclined surfaces, composed 

 of till and stratified gravel. Considering these facts, together 

 with the proofs of recent elevation of this coast, hereafter to 

 be mentioned, I cannot doubt that this till was accumulated 

 in a sloping sheet beneath the waters of the sea. In compo- 

 sition it resembles some of the beds of till in Terra del Fuego, 

 which have undoubtedly had this origin. I presume the 

 scored, rounded, and striated boulders were pushed, in the 

 form of a terminal moraine, into the sea, by the great glacier 

 which descended Nant-Francon. 



Mr Trimmer* reports, on the authority of some workmen^ 

 that sea-shells have been found on Moel Faban, two miles 

 N. E. of Bethesda. I ascended this and some neighbouring 

 hills, but could find no trace of any deposit likely to include 

 shells. This hill stands isolated, out of the course of the 

 glaciers from the central valleys ; it exceeds 1000 feet in 

 height, its surface is jagged, and presents not the smallest 

 appearance of the passage of glaciers ; but high up on its 

 flanks (and perhaps on its very summit), there ai'e large, an- 

 gular, and rounded boulders of foreign rocks. 



Along the sea- coast between Bangor and Caernarvon, and 

 on the Caernarvonshire plain, I did not notice any boss-formed 

 hillocks of rock. The whole country is, in most places, con- 

 cealed by beds of till and stratified gravel, with scattered 

 boulders on the surface ; some of these boulders were scored. 

 From the account given by Mr Trimmer t of his remarkable 

 discovery of broken fragments of Buccinum, Venus, Natica, 

 and Turbo, beneath twenty feet of sand and gravel, on Moel 



* Proceedings of the Geological Society, vol. i. p. 332; or Phil. Mag. 

 S. 2, vol. X. p. 143. Mr Trimmer was one of the earliest observers of tho 

 scores and other marks on the rocks of North Wales. lie also remarked, 

 that " some of the larger blocks amid the gravel have deep scratches on 

 their surface." Mr Trimmer himself found broken sea-shells in the dilu- 

 vium at Beaumaris, 



t Proceedings , of the Geological Society, vol, u p» 332; Phil, Mag , 



\oc. Cl't, 



