264 Scientific Proceedings, Royal Dublin Society. 



tions noticeable according to the distance from its source. Close 

 to the cliff are the larger fragments piled up on one another, and 

 lacking the decided parallel arrangement found in other portions 

 of the deposit. Sometimes a loam or sand fills the spaces between 

 the fragments ; sometimes the spaces are open. This first-formed 

 part of the head is quite comparable with ordinary screes. In 

 the upper parts, and those further from the cliff, the fragments are 

 generally smaller. They are packed closely together, and always 

 dip away from the cliff at low angles. The interstices between 

 the fragments are invariably filled in by loam. Lenticular bands 

 of loam, lying parallel to the fragments, occasionally occur in all 

 parts of the head, but are frequent in the most seaward sections. 

 They often have small slivers of slate imbedded in them. The 

 loam represents the finer material derived from the waste of the 

 cliffs. The bands or streaks in which it occurs, together with the 

 parallelism of the fragments, give an appearance of rude stratifica- 

 tion to the deposit (see Plates XXVII. and XXVIII.). 



The accumulation of the head all along the coast is due to the 

 pre-glacial shore platform subtending the base of the cliff, and 

 catching all the material brought down on to it. It probably 

 never accumulated inland to the same extent, owing to the absence 

 of these conditions. 



The pre-glacial cliff is always rounded off at the top — a feature 

 due to its waste at the time the head was formed. 1 The pre- 

 glacial coast-line can be traced by this feature even where the 

 platform and overlying drifts have been entirely removed by 

 recent erosion, as on the greater part of the Waterford coast 

 (see fig. 3). 



Since there is no head accumulating along the south coast of 

 Ireland at the present day, its formation must indicate a change 

 of climatic conditions. The angularity of the fragments, and 

 their origin from the adjacent heights, point to the action of 

 frequent frosts or rapid alterations of temperature. As already 

 pointed out, the inner portion of the head near the old cliff is 

 quite comparable with modern screes. With respect to the greater 

 portion of the head, however, the distance to which it extends 



1 For the form assumed by cliffs in consequence of disintegration, see "On the 

 Disintegration of a Chalk Cliff," by the Rev. 0. Fisher, Geol. Mag., vol. in., 1866, 

 p. 354. 



