System cannot he of the age of the Old Bed Sandstone. 125 



line of the culm-measures in the north of Devon, are brought 

 up in the south through the upper culm-measures, throwing 

 them, and at times irregular portions of the overlying killas, 

 off on either shoulder with a counter or reversed dip north 

 and south, as I have before explained at Ashton and Doddis- 

 comb Leigh. This great dynamical axis extends from Dod- 

 discomb Leigh, near Exeter on the east, to the western ex- 

 tremity of South Tregear Down, at Tor-Park Water on the 

 north-west of Launceston, where, by a moderate declination, it 

 becomes depressed below the upper culm-measures ; and be- 

 tween this and the sea, a distance of ten miles, is only met 

 with again on this range in one instance, which I shall shortly 

 notice. Now if I had nothing more to advance, the evidences 

 connected with this great southern axis never could be shaken, 

 but wherever nature proclaims any great truth she is sure to 

 be lavish of her proofs. The Coddon Hill grits of the north 

 of Devon, with their Posidonia limestones, are brought up on 

 the south, and in the range I have mentioned. No one dis- 

 putes the fact; but they are protruded with a reversed dip 

 through the upper cidm-measures, and do not trough up from be- 

 low them, in the way they ascend in the north of Devon. The 

 southern parallel, or fractured counterpart of the upper culm- 

 measures, ranges from the south of South Tregear Down, 

 branching off there from the floriferous in mass, and extends by 

 Launceston and Heathfield to Dartmoor. Now that southern 

 range, repeatedly alternating with, and finally underlying, the 

 killas, altogether negatives the supposition, that the killas 

 may be a member of the Exmoor group below the Coddon 

 Hill grit. The fact is an insuperable bar to any such hypo- 

 thesis. In consequence of the depression of No. 8 at South Tre- 

 gear Down, the upper culm-measures only are exposed from 

 thence to Boscastle. All parties fortunately are agreed 

 that the black culmy slates of Boscastle and Forrabury Cliffs 

 are either carboniferous, carbonaceous, or floriferous, — Dr. 

 Boase, Mr. De la Beche, Professor Sedgwick, Mr. Murchi- 

 son, Mr. Phillips, and myself. In truth, if we follow the coast 

 line from Clovelly and Hartland Point on the north, we bring 

 them with us in unbroken continuation to Boscastle, where, 

 and within any radius of five miles, we meet with no intrusive 

 igneous rocks. The beds have been affected about here in 

 only a trifling degree by the great anticlinal axis which is so 

 amply exposed on to the west extremity of South Tregear 

 Down, ten miles to the eastward; they have, however, been af- 

 fected by it, for they all dip to the north at a low angle, com- 

 monly 10^, rarely 1 tliink exceeding IS*^, so that a line drawn 

 due south from Valency bridge and Forrabury church, to the 



