30 



THE GEOLOGIST. 



thereto. The mass of rocky strata which more prcperly appertains 

 to Hook has an age much more recent, and the older rocks have 

 undergone not only consolidation, but have been subjected to the 

 action of violent subterranean forces, which have bent, twisted, and 

 elevated the older masses, long previous to the period when the 

 conditions prevailed which gave rise to these newer rocks which make 

 up the headland of Hook. Those more ancient rocks have to a con- 

 siderable extent furnished the materials out of which a portion of the 

 Hook promontory was constructed, and they afford evidence that, 

 after the twistings and elevations referred to, a portion of their area 

 formed the margins of the sea from whence resulted the rocky masses 

 which more immediately support the Carboniferous limestones of Hook 

 Point. The western side of Hook, at a small bay near the village of 

 Templetown, among the rocks of the coast, gives us an insight into 

 the physical causes which were the prelude to those conditions from 

 which the limestones, rich in organic remains, emanated. Here we 

 find coarse sandstones, and sometimes there are what are known to 

 geologists under the name of conglomerates, consisting of rounded 

 pebbles cemented together by a sandstone-base, and recording in their 

 structure the fact of their having been originally fragments broken 

 by the action of ancient waves from previously existing rocky coasts, 

 and afterwards ground upon each other, each one rubbing from its 

 neighbour its angularity and asperities in the same manner that we 

 find, at the present time, the sea-margins of even rocky coast fringed 

 by an outline of pebbly beach, the result of the force and abrading 

 power of the ever-restless ocean. 



These conditions of an agitated sea, preceding the formation of the 

 newer and overlying rocks, were succeeded by features of a more 

 tranquil nature, with respect to the ancient physical geography of 

 this portion of Ireland. The sandstones became gradually less coarse ; 

 and in the strata which are intermediate between the conglomerates 

 below and the limestones above, traces of organic beings begin to make 

 their appearance. These consist of fragments of laud-plants, having 

 a coaly aspect, and, on the whole, indistinct as to their characters. 

 They bear about them sufficient evidence to show that they formerly 

 flourished on the surfjice of the earth as the stems of ferns ; and 

 from tlieir nature and geological position, there is strong reason for 



