898 T. G. BONNE Y ON THE SERPENTINE AND 



which appear impracticable, consist of serpentine; but some of the 

 jutting reefs below resemble hornblende schist. 



Descending into Polbarrow Cove by a narrow track, we find that 

 the southern part of it consists mainly of hornblende schist ; but 

 there are intrusive veins of serpentine in it close to a natural arch, 

 as well as in the little ridge of schist, on the middle of which stands 

 a small boathouse. Serpentine may also be seen in a quarry above 

 the cliff south of the boathouse. Just north of this is a junction of 

 the schist with the serpentine, which runs obliquely in this direction 

 up the cliff. It now continues for some time ; but two low headlands 

 which bound the cove are capped by hornblende schist ; and the 

 next one to north is wholly of that rock. There is a gabbro vein 

 in the schist, near the junction with the serpentine, about on a 

 level with the boathouse, and another much higher up the cliff in 

 the latter rock. 



Returning to the cliff we come to a small quarry showing a 

 junction of hornblende schist and serpentine. The former rock dips 

 about 27° E.N.E., and in 1873 could be seen to be overlain irre- 

 gularly by the serpentine. In one part of the quarry a piece of the 

 schist was intercalated between serpentine. In 1876 the relations 

 were less clear. The schist is very dark and full of hornblende. 

 The specimen described above was collected here. The cliffs, as 

 may be seen from the geological map, consist of hornblende schist 

 from this spot to near Cadgwith, when we come to another junction 

 in the celebrated Devil's Frying-pan, obviously an old sea-cave 

 whose roof has fallen in. 



The relations of the serpentine with the schist, as seen by de- 

 scending into this hollow, leave no doubt that the former rock is 

 intrusive. On reaching the shore we find ourselves at the bottom 

 of a funnel-shaped pit communicating with the sea by a natural 

 archway. This, and the greater part of the two adjoining sides, is 

 of hornblende schist, which dips westward at an angle of 40° to 50°, 

 increasing gradually to about 70° towards the west on the southern 

 side, and rolling over considerably on the northern. The remaining 

 side is serpentine. 



The junction at the S.W. corner is masked by debris ; but on the 

 other it is clearly an intrusive one, a large fragment of schist being 

 entangled between two masses of serpentine. I think that the pre- 

 sent summit of the entrance archway also marks a former junction 

 with the serpentine ; for the schist of this looks much disturbed and 

 slickensided, and has a "junction " aspect. Also an overlying block 

 apparently in situ is serpentine. The serpentine is dull mottled 

 blackish brown and red in colour, full of small glittering scale-like 

 crystals with a rather silvery lustre, as at Mullion and at Pradanack 

 Quarry. 



After climbing back to the pathway leading to Cadgwith, the 

 descent into that village is mainly over serpentine. But the rocks 

 exposed in the little cove forming the harbour are very characteristic 

 hornblende schists, dipping about 35° N.N.W. 



On reaching the summit of the steep ascent which leads from 



