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lY. 



THE BEAUEOHT'S DYKE, OEE THE COAST OF THE MULL 

 OE GALLOAYAT. By G. H. KK^AHAIT, District Surveyor 

 (Retired), H. M. Geological Survey. 



[Plate Y.] 



[Read, April 21, 1900.] 



The proposed construction of a Submarine Tunnel from Ireland to 

 Scotland has developed attention to one of the most remarkable natu- 

 ral phenomena in connexion with the actions of wind and tidal 

 currents in the deep sea — that is, the travelling sands and gravels, 

 and their adjuncts, in the gulch called the "Beaufort's Dyke," off 

 thecoast of the Mull of Galloway. 



In the sea between Ireland and Great Britain there are various 

 perplexing and unexplaiaed deep-sea currents that go under various 

 names according to the localities, such as — races, dykes, ditches, 

 undersucks, etc. These are conspicuous in connection with the sand- 

 banks off the Leinster coast. The "races" are not the ordinary 

 " tidal race" in a narrow channel, but a current that starts off nearly 

 perpendicularly to the coast line, towards the "tail" of one of the 

 banks. All these different currents vary in accordance vrith the state 

 of the tide ; being generally more conspicuous during the spring tides 

 than the neaps. These variations, especially of the undersucks and 

 ditches, are so vagrant that, as a general rule, the fishermen are 

 afraid to shoot their nets inside the banks off the south-east coast. 

 On this account it was proposed, some fifteen years ago, that the Royal 

 Society should apportion a part of their Scientific Grant to inves- 

 tigate these obscure currents. As, however, at that time, there was 

 no competent person disengaged, who would undertake the investi- 

 gations, the proposal fell to the ground. 



All these peculiar currents are of great interest ; but, at the 

 present time, we are specially engaged with those that have a con- 

 nexion with the "Beaufort's Dyke." Formerly all the best authorities 



