Ch. IV.J SCHISTOSE GROUP OF CORNWALL. 



Fig. 1. 



51 



Elvan Course, near Penzance. 

 (Ground Plan.) 



for seven hundred feet : and although the course is very irre^- 

 gular in the part selected, the remainder of it, on the side 

 exposed, exhibits a line very slightly undulated. As regards 

 the dip of this el van there seems to be a difference of opinion, 

 Mr. Hawkins having stated that it underlies, in the Wherry 

 mine, towards the S. W. one foot and a half in a fathom *, 

 whilst Mr. Carne says that it dips north, f The appearance 

 of the dip is very various : at A, it is S. by E. at 45 ; 

 at B, N. W. at 70 ; at C, it underlies the slate towards the 

 S. E. very gently, and in a curved line, which, at a distance 

 of ten feet, attains rather a higher level ; at D, it is nearly 

 perpendicular ; on the northern side, at E, F, and G, the dip 

 is uniformly to the N. W. at angles fluctuating between 60 

 and 70. Now the more extended surfaces of the large con- 

 cretions, in the middle of the course, generally dip at low 

 angles to the southward, either E. or W. of this point, according 

 to the curvature of the elvan ; whilst the lesser surfaces de- 

 cline in an opposite direction at elevated angles ; and we 

 therefore consider these to be the true bearings : the latter 



* Gcol. Trans, of Cornwall, vol. i. p. 140. 



E 2 



f* Idem, vol. ii. p. 82, 



