AND CAHORE SHINGLE BEACH, CO. WEXFORD. 



35 



back wash (A, fig. 1) of each wave will carry a quantity of sand and 

 the like with it, which at the junction (B) with the incoming wave 



Fig. 1. — Diagram of a Wind-wave breaking on a shelving beach. 



will be met, tossed about, and carried back again ; but if the tide is 

 ebbing, scarcely any particles will be carried by the back wash, and 

 the junction (B) with the incoming wave will scarcely have even a 

 particle of sand in it. In the first case, a bucketful taken at the 

 junction would be sand and water, while in the second it would bo 

 nearly pure water. 



Third Point. — "Currents carry the smallest fragments furthest." 

 Tidal currents are different from other currents. They break on the 

 shore in successive waves, whether these be augmented by wind- 

 waves or not, drive the fragments obliquely up the beach, the larger 

 ones to remain or only to be brought back a little way, while the 

 smaller ones are caught in the " back wash," and carried back again 

 till they meet the succeeding incoming wave. Thus the larger frag- 

 ments have a tendency to be driven higher, and further up, and 

 along a beach than the smaller ones. Also, if the progress of a 

 beach is stopped by a groyne, whether natural or artificial, the 

 larger pebbles accumulate behind it, and form a shingle beach. 



Chesil and Cahore beaches are remarkable on account of their 

 being very similarly circumstanced in several particulars; this will be 

 evident from the following table of comparison. All the statements 

 in regard to the Cahore beach are given from personal examination ; 

 but for those relating to the Chesil beach we have to rely on the 

 notes and publications of other observers. Some of the points of 

 comparison are partly speculative, but agreeable with the known 

 results of certain natural laws. 



A Comparison of the Conditions at the Chesil Beach, Dorsetshire, 

 and at the Cahore Shingle Beach, co. Wexford. 



Chesil Beach. 



1. The beach is situated on 

 the north side of the English 

 Channel, where there is a smaller 

 "rise 1 ' of the tide than on the 

 south side (coast of France). 



Cahore Shingle Beach. 



1. The beach is situated on the 

 west side of the Irish Sea, where 

 there is a smaller "rise" of the 

 tide than on the east side (coast 

 of England). 



d2 



