54 THE DENUDANTS, OR CARVERS OF 



under the erratic blocks, while inland similar pedes- 

 tals are seldom three inches in height. In Galway 

 it is known, by the veins of segregation (granityte) 

 in the granite, that rocks of this class have weathered 

 in the proportion of two to 'one, as they are respectively 

 at, or away from, the sea. 



The sea also appears to affect the colour of some 

 rocks. In Kerry, inland, the purple rocks weather red, 

 and those of a green colour, yellow. At the coast the 

 first become a whitish blue, while the green only 

 seem to be given a brighter tinge; and on the north 

 of Galway Bay the Felstones near the coast were 

 remarked to weather into a colour different from that 

 of the same rock when inland. Marine action is 

 often represented as forming a plain of denudation ; 

 but marine plains are not necessarily formed by 

 denudation, as they seem to be as often due to filling 

 up as to denudation. This is evident when tracing 

 any old sea margin, such as the 350 feet sea-beach in 

 Ireland, which is more often marked by the terraces 

 due to filling up than by the steps cut in the hill- 

 sides. To form a true plain of denudation the land 

 ought to be perfectly stationary ; and then, the active 

 part of the sea being at the level of the breakers, a 

 plain may be cut ; but even then there are so many 

 different causes to affect it, that rarely off a coast-line 

 will a true plain of denudation exist. If the sea is 

 working on homogeneous or nearly homogene6us rocks, 



