330 DR. J. A. SMYTHE ON 



Two newly-discovered Whin-Dykes on the Coast of 

 Northumberland. 



By J. A. Smythe, Ph.D., D.Sc, Armstrong College, 

 Newcastle-on-Tyne. 



Along the coast-section which stretches from the Seaton 

 Burn to the mouth of the Tyne there occur three well-known 

 basaltic dykes, accounts of which have, at times, been 

 published by various authors.* Taking these dykes in order 

 from the north, the first is exposed at Seaton Sluice, a little 

 south of the harbour ; the next, ^-mile south of this, hard by 

 the Colly Well, from which it takes its name ; and the third, 

 the Tynemouth dyke, occurs almost at the extreme south end 

 of the section, close to the North Pier. 



During the autumn of last year (191 2), two other dykes, 

 which appear to have escaped notice hitherto, were observed 

 by the author, and it is the object of this paper to record 

 their position and some points of interest connected with 

 them. One of these dykes crops out on the foreshore at the 

 north end of the Whitley sands, just 100 yards south of the 

 Brierdene Burn ; this will be referred to as the Whitley Dyke. 

 The other is well exposed in the cliff-section near Hartley, 30 



* G. A. Lebour, "Outlines of the Geology of Northumberland and 

 Durham," 2nd edition (1886), p. 86. 



J. J. H. Teall, " Petrological Notes on some North of England 

 Dykes," Quart. Journ. Geol. Soc, vol. xl. (1884), pp. 209-46; also Geol. 

 Mag., dec. iii., vol. vi. (1889), p. 481. 



M. K. Heslop, " On some elementary forms of Crystallisation in the 

 Igneous Rocks of Northumberland and Durham," Proc. Univ. Durham 

 Phil. Soc, vol. iii., pt. 2 (1909), p. 37. 



M. K. Heslop and J. A. Smythe, "The Dyke at Crookdene, North- 

 umberland, and its Relations to the Collywell, Tynemouth and Morpeth 

 Dykes," Quart. Journ. Geol. Soc, vol. lxvi. (1910), pp. 1-iS. 



