292 The Irish Naturalist. December, 



The raised beach gravel is cemented by oxides of iron. 

 The blocks which lie on the platform and embedded in the 

 gravel sometimes attain a length of lo feet. They are of 

 similar natnre to the rocks in the pre-glacial cliff above, having 

 fallen from it dnring the formation of the beach. 



The blown sand overlies the beach gravel and blocks, and 

 is banked against the old rock-cliff behind the head, which 

 has obviously slipped down little by little over it. 



The head is composed of angular material derived from the 

 waste of the old rock-cliff against which it is banked. The 

 parallelism of its fragments gives it an appearance of stratifi- 

 cation when viewed from a distance. 



The boulder-clay is a stiff clay containing scratched stones, 

 some of which have been transported for long distances. It 

 was laid down by ice moving out to sea over the top of the 

 cliff. It is to their position in the lee of the cliff, as well as 

 to the feebleness of the glaciation, that the pre-glacial deposits 

 owe their preservation. 



The upper head is similar to the lower, but contains a small 

 number of sub-angular and rounded stones derived from the 

 boulder-clay. 



The outstanding stack, figured in the diagram, shows that 

 the drift deposits originally covered a much greater portion of 

 the platform. 



The above may be taken as typical of a number of sections 

 to be seen all along the south coast of Ireland from Carnsore 

 Point to Baltimore. The complete series of deposits is, how- 

 ever, not always represented. Sometimes one member is 

 absent, sometimes another, but the succession is invari- 

 able. 



The superposition of the boulder-clay proves the pre-glacial 

 age of the lower head and raised beach. The lower head in its 

 turn marks a period before the oncoming of the ice, when 

 debris from the old sea-cliff accumulated on the beach, after it 

 had been raised above the reach of the waves. The occurrence 

 of blown sand close down to the rock-platform indicates that 

 elevation commenced before the head began to accumulate. 

 As regards the amount of this elevation, observations made all 

 along the coast show that the difference in level between the 

 pre-glacial and modern shore-platforms is about 12 feet. The 

 head is, however, being at present removed by the sea, so that 



