r26 Rev.W. D. Conybeare on M. de Beaumont's Theory. 



in length, must have subsequently been effected by denuding 

 causes of the most violent agency, excepting where a single 

 frao-ment of it was sheltered from their action by the depres- 

 sion occasioned by this great fault. On the coast south of Cul- 

 lercoats this same sandstone is traversed by a basaltic dyke : it 

 is true that our evidence as to the date of the convulsions ex- 

 tends only in Northumberland to the magnesian lime, and in 

 Yorkshire to the alum shale ; yet the general analogy of the 

 two cases may incline us to consider them as contempora- 

 neous : but the question will still remain, how much younger 

 they may be than the age of the most recent of those rocks 

 which is associated with the inferior oolite. Their direction is 

 nearly, but not exactly parallel, both ranging nearly E. and 

 W.; but the eastern extremity of the main Newcastle dyke in- 

 clines a litde to the north, and that of the Cleaveland dyke to 

 the south. The general direction of the faults affecting the in- 

 termediate (Durham) coal-field is nearly similar; and the cir- 

 cumstances I have mentioned render it very desirable to trace 

 the prolongation of their lines towards the overlying range of 

 magnesian limestone, and to examine how far this rock ap- 

 pears affected by them. In the paper on the magnesian lime- 

 stone, in the Geol. Trans. 2nd series, vol. iii. some trifling 

 faults affecting this rock in Yorkshire are noticed ; but their 

 general direction seems to be at right angles to those now no- 

 ticed, and parallel to the general elevation of the strata. 



The traces of the oolitic formations in Scotland have been 

 much disturbed : those in the islands of Mull and Skye by the 

 eruption of the trap rocks, (as we have already noticed, p. 123,) 

 most probably during the tertiary period. The lines of direc- 

 tion are here very variable: along the coast of Sutherland, 

 near the Brora coal-field (which, as in the eastern Moorlands 

 of York, is associated with the inferior oolite), the lias and 

 oolites come in contact with the granitic mountains, and are 

 much disturbed, the lines of direction being variable, but ge- 

 nerally inclining to parallelism with the primitive chains which 

 rano-e N.E. and S.W. Although these disturbances are in 

 juxtaposition to the elevated primitive chains, it would be too 

 hasty an inference to refer them to the jirotrusion of the gra- 

 nite; the granite may already have assumed its actual posi- 

 tion relative to these superstrata, and both the primitive and 

 secondary formations may have appeared together at some 

 later epoch. As we have here no younger formations than the 

 oolites to afford us the means of com})arison, we must be un- 

 able to pronounce definitively how recently these convulsions 

 may have taken place. 



[To be continccil] 



