SOUTH-WEST IRELAND. 189 



the present bay the sea has been so long at work, 

 that nearly all the old gravels have disappeared, 

 and it is now clearing out what still remains of the 

 boulder-clay, besides doing some rock denudation. 

 Meteoric abrasion has not as yet been mentioned ; 

 it must, however, have materially aided the sea, 

 both during its advance and retreat, as it is still 

 doing at the present day. 



Here we may digress and point out the nature of 

 estuarine deposits, and of the fossils and pebbles 

 found in them. In some estuaries the gravels and 

 sands will be sharp and clean, like those on an open 

 seaboard ; but in most estuaries they are more or 

 less dirty, clayey, or peaty, from their vicinity to the 

 land, and the inability of the sea, confined as it is, 

 to wash them properly ; or storms may bank up the 

 water during floods, and cause all the dirt brought 

 down by the rivers to be deposited inside. In Wex- 

 ford Harbour, on the south-east of Ireland, during 

 gales from the south-east, the water has sometimes 

 been four feet higher than ordinary spring-tides. 

 Some estuary deposits have been mistaken for 

 glacial-drift, while in reality they are only the 

 washing and rearrangement of such kinds of drifts. 

 In many places on the coast of Ireland the sea is 

 bounded by high glacial-drift cliffs which are yearly 

 more or less denuded. In summer weather shelly 

 sands and muds may be deposited close up to these 



