1904. Wright & VLv^-^.—Pre-glacial Beach, S. /re/and. 293 



a somewhat gi'eater uplift must have taken place in order to 

 allow of its accumulation. We have no means at present of 

 determining the amount of this elevation, but it must have 

 been at least 10 or 20 feet above present level. It may have 

 been immensely greater. 



With regard to the climatic conditions during the formation 

 of the head or rubble-drift there is little to be said. Its general 

 similarity to modern screes suggests the action of frost or of 

 rapid alterations of temperature in shattering the rocks from 

 which it was derived. There are two points, however, in which 

 it differs materially from ordinary screes, and which seem to 

 indicate the action of periodic heavy rains : namely, the 

 amount of loam and sand it contains, and the distance the 

 finer material is carried from the cliff. 



The occurrence above the boulder-clay of a rubble-drift 

 similar to the lower head, indicates a return of similar condi- 

 tions after the ice had melted away. 



Before leaving this question of climate it is worth calling 

 attention to the fact that a few erratics derived from districts 

 a considerable distance to the east were found in the under- 

 lying raised beach gravels. For the transport of these it is 

 almost necessary to suppose the existence of floating ice, and 

 it may well be, that the lowering of temperature thus indi- 

 cated may have been intensified during the formation of the 

 head, and may finally have culminated in the invasion of the 

 district by land ice. 



The finding of the raised beach along the shores of the sub- 

 merged river-valleys of the South of Ireland is a point of con- 

 siderable interest ; showing, as it does, that their submergence 

 took place in pre-glacial times. It may thus be said in summing 

 up that we have evidence of the following sequence : — 



1. I^and higher than at present — erosion of valleys now 



submerged. 



2. I^and depressed to about twelve feet below present 



level — formation of raised beach. 



3. lyahd again elevated to an unknown extent above its 



present level — accumulation of blown sand and 

 lower head. 



4. Advance of the land ice over the whole south coast 



of Ireland, and deposition of the boulder-clay. 



5. Accumulation of the upper head. 



