124- THE RELATIVE POSITION OF THE [Ch. VII. 



against the mass of granite. No general conclusion can, 

 therefore, be drawn with respect to this connection; since 

 even the slight kind of conformity visible at one point of 

 junction, may not be continued perhaps for ten yards.* 



This accords with the position of the slate in Cornwall, 

 near its junction with the granite ; as will be seen by the 

 following remarks of Professor Sedgwickf on this subject : 



" At the junctions of the granite with the slate, the latter 

 rock may be generally observed to dip from the mass of the 

 former ; yet the inclination arid line of bearing of the slate 

 are not found universally to correspond with the surface of 

 the rock on which they rest. Thus, in crossing from Mara- 

 zion to St. Michael's Mount, the slates suddenly change 

 their dip, and rise towards the granite of the Mount ; but 

 though they undoubtedly rest thereon, yet their beds do not 

 reach an inclination of more than 10 or 12, and conse- 

 quently appear rather to abut against, than repose upon, the 

 almost perpendicular mass of granite. Again, the slate which 

 commences to the west of Lamorna Cove, has nearly a uni- 

 form dip towards the E. and S. E. : and the line of bearing 

 of its strata does not afford any indication of the very uneven 

 surface of the granite on which they rest. The whole mass 

 of slate appears to repose obliquely on the granite, and at its 

 western junction rises into high cliffs, the upper beds of 

 which spread over the fundamental rock, while the lower 

 beds seem to lean against, rather than repose upon, the pre- 

 cipitous face with which they are in contact. At the eastern 

 junction of these rocks, the slate rests on the granite ; but in 

 such a position, that their great line of cleavage, if produced, 

 would abut against the headlands of the latter rock." 



This disposition is well exemplified at Mousehole, on the 

 same range of coast, where the junction of the granite and 

 slate is exposed for more than a hundred feet in length, run- 

 ning in an undulating line across the direction of the strata ; 



* Western Islands of Scotland, vol. ii. p. 353. 



f Trans, of the Philos. Soc. of Cambridge. On Devon and Cornwall. 



