DEPOSITS AND ELEVATION. 13 



elevation of each Head above the water-level has taken 

 place since those seas bore icebergs, and in fact at a time 

 more recent than the prevalence on this particular spot of 

 land-ice. 



There are not wanting certain indications which may 

 possibly imply a former continuity between the boulder- 

 clays of Llandudno and Penmaenbach ; but this question 

 and the consequent hypothesis of a subsequent diversion of 

 the course of the Conway river from an ancient debouch- 

 ment to the eastward into its present estuary do not fall 

 within the scope of the present essay. 



'B. Sea-beach and Beach-marks. 



In order of antiquity I take the highest first. Mr. 

 Binney (Manchester Greol. Soc. Trans. 1 861-1862, p. 99) 

 has described what he calls a singular bed of shingle at an 

 elevation of 400 feet from the sea-level, at a point on the 

 " old road/^ a little to the east of where the road to St. 

 Tudno^s Church branches ofip. This is a very peculiar 

 deposit, and will be discussed in detail in the sequel. 



There are to be seen on most parts of the Head, where 

 the limestone rock is bare, large isolated masses of the 

 like stone, more or less rounded and weathered. One of 

 these has been figured by the Rev. T. G. Bonney (Geol. 

 Mag. iv. pi. xii.) apparently, though the statement is not 

 definitely so framed, as an indication that the surface of the 

 higher ground has in many cases been afi*ected by ice. These 

 blocks occur in considerable numbers on the north-western 

 region of the Head. They lie on the bare rock, sometimes 

 conformably, but often er not, and are of course much 

 weathered. Some have already been subjected to the 

 more obvious disintegration of frost-splits, and lie in frag- 

 ments. There are two characteristic blocks of this kind 

 near the eastern ends of two reefs of rock which cap the 

 more precipitous portion of the southern declivity. 



