THE EARTH'S SURFACE SEA ACTION. 57 



island, meteoric abrasion is acting very similarly on 

 the same beds. It may also be seen in numerous 

 places on the coast of England. The sea, nearly 

 everywhere, tries to follow the softer beds under the 

 chalk, and would do so but that the inhabitants have 

 for ages placed barriers to protect these soft parts of 

 the coast from the ravages of the sea, but the chalk 

 they can leave unprotected; while inland, meteoric 

 abrasion has modified the chalk cliffs into slopes, 

 and is said to be also wearing away the underlying 

 softer beds. In Ulster, Ireland, there are also chalk 

 escarpments, due both to marine and atmospheric 

 denudation. This subject will, however, have to be 

 again referred to when we are comparing submerged 

 and elevated sea-formed valleys. 



The rock, or rather the debris of the rocks (Fault- 

 rock), included between the walls of a fissure, is in 

 many cases softer and more easily denuded than the 

 associated rocks. The waves will work with vastly 

 greater effect in such fissures than on the adjoining 

 rocks, and thereby excavate long narrow guts that 

 may be of great length, although only a few yards 

 wide. Many straits have evidently been so formed, the 

 sea working along, and excavating out a dyke of 

 fault-rock across a promontory, thereby eventually 

 forming an open fissure, and dividing one portion 

 of the land from another. Some of these guts are 

 open to the sky, but others may occur as long, 



