284 Mr D. Milne on Earthquake' Shocks in Great Britain^ 



Highlands owes its elevation to the outburst of these primi- 

 tive traps. Nor is it unimportant here to remark, that in 

 Calabria,* Pignerol,-)- Connecticut^^ the Caraccas,§ and other 

 countries where earthquake-shocks have been both frequent 

 and severe, the rocks are generally primitive, abounding also 

 in ancient porphyries. According to Daubeny, the volcanoes 

 of Auvergne, Cantal, Styria, and the Canaries, are situated in 

 granitic rocks. 1| 



It is true that in several parts of England, where shocks 

 have been very frequent, as in the southern counties, and in 

 Derbyshire, rocks of this character do not prevail. But in 

 these districts there occur numerous and extensive " faults" 

 which must go deep into the bowels of the globe. For ex- 

 ample, each of the Tyndale and Craven faults in Yorkshire 

 runs from at least fifty to sixty miles ; and several of them 

 have produced a vertical displacement of the earth'*s crust to 

 the extent of from 3000 to 4000 feet. In the South Wales 

 coal-field, there is an axis of dislocation which runs from the 

 Bristol Channel through the Mendip Hills and Somersetshire, 

 and " in the line of its projection to the east is the coeval dis- 

 turbance of the coal from near Boulogne, through Belgium 

 and Westphalia, and in the south of Ireland."1[ One of the 

 faults in the Colebrookedale coal-field has been shewn by Mr 

 Prestwick to manifest a vertical displacement of no less than 

 1000 feet.* * Then, again, in the south-east coast of England, 

 there are two great axes of elevation running east and west, 

 the one through the Isle of Wight, and the other dividing 

 the London from the Hampshire basin, both of which have 

 been traced into the continent, and have, in all parts of their 

 extensive course, produced great vertical movements. This 

 series of faults, still preserving the same general direction, 

 has been traced by M. De la Beche, through Devonshire and 

 Cornwall. 



* Pinkerton's Voyages, vol. v., p. 282. t Journ. de Phys., t. 67. 

 X Silliman's American Journal of Science, xxxix. p. 341. 



§ Humboldt's Person. Narr., vol. iii. p. 4. 



II Daubeny on Volcanoes, p. 384. 



% Phillip's Treatise on Geology, p. 115. 



• « Silurian System, vol» iii., p. 110. 



