104 The Hon. H. G. Bennet on a Whin Dyke. 



The specimens that accompany this paper will shew to the com- 

 mon observer the difference between the limestone when in contact 

 with, or at a distance from the dyke, as well as that between the 

 dyke itself and the ordinary whin rocks of the county, such as those 

 which are found on the Cheviot, and which form large masses on 

 that range. Indeed all the whin dykes that I have seen in the 

 northern district of Northumberland, the two which are so near to 

 each other in Holy Island, and those which form the Fairn Islands, 

 no less than that at Beadnel, bear a striking and uniform resemblance 

 to each other j and are unlike those ranges of whin which are com- 

 posed principally of hornblende, and which prevail to such an extent 

 m the north-western parts of the county. 



