igii- HiNCH. — High-level iMarine Shells in Co. RIayo. 191 



levels from 100 to 800 feet above sea-level.^ The authors 

 do not commit themselves to the theory that the deposits 

 are " sea beaches," and indeed state that they only bring 

 the matter forward in order to request an explanation of 

 the facts, but the impression left on those who heard the 

 paper read was that they were inclined to regard the usual 

 theory favorably. The list of mollusca found was sugges- 

 tive of human influence, and some of those present were 

 content to keep an open mind on the subject. The cases 

 were, however, ones to be investigated if possible, and on 

 my return from Clare Island in July of the present year 

 I visited the chief locality mentioned by Messrs. Dixon 

 and Gordon. About three and a half miles west-south- 

 west of Mallaranny the road to Achill Sound runs through a 

 small valley which is bounded on the north and south by 

 low cliffs, and is here about 100 feet above sea-level. In the 

 crevices of the cliffs the shell deposits occur. The solid 

 rock of the district is of Old Red Sandstone age, and consists 

 of tabular sheets of pebbly conglomerate about one foot in 

 thickness separated b}' flaggy micaceous sandstones, the 

 whole series dipping ver}'- regularly south towards Clew 

 Bay at an average of 10°. The differential weathering 

 which has taken place is very marked, and can be seen 

 strikingly developed on the sea-shore a few hundred yards 

 distant. Here the waves have swept away the flaggy 

 sandstones from between the sheets of conglomerate, and 

 while the conglomerate itself is able to resist the onslaught 

 of the sea, the steady undercutting which is going on even- 

 tually brings down great masses of rock. This marine 

 erosion has its counterpart in th^e inland valley, and while 

 the sub-aerial erosion is trifling compared with that effected 

 by the waves, the results are still considerable and ha\^e 

 a distinct bearing on the problem. A talus has been formed 

 at the foot of the low cliff by the tabular masses and mono- 

 liths of conglomerate which ha\^e fallen as the result of 



1 Gordon and Dixon : Deposits of unbroken marine shells at high levels 

 in the Curraun Peninsula, Co. Mayo. Sci. Pvoc. Royal Dublin Society, 

 xi., 1905-08. pp. 325-3-27- 



