Cornwall and South Devon. 339 



fication or analysis of the Cornish killas: at present I can 

 only express myself generally, by observing that whether 

 coarse arenaceous schist obtains in some localities, or red and 

 gray grits, either passing into quartz rocks, or thickly inter- 

 sected by quartz veins, predominate in others, a sufficient 

 proportion of the lesser ingredients is uniformly present or 

 close at hand to determine their inseparable relations. 



It contains nearly all the lodes of tin and copper (including 

 those of the granites which have been generated by its re- 

 duction in the volcanic furnaces) of any value in the killas 

 group, except the inferior mines about Tavistock*, and on 

 either side of Hingston down, between Tavistock and Cal- 

 lington. One of its lodes at Carn-brea, has probably yielded 

 as much ore as all those Tavistock and Callington mines 

 together. 



All the coral limestones of Torbay, from Babbacombe to 

 Berry head, are included in its upper terms there, which is 

 sufficiently shown by its lower arenaceous schists and grits, 

 such as overlie the Plymouth limestones of Mount Batten and 

 Plymstock, being protruded through the Torquay f and Brix- 

 ham limestones, viz. at Meadfoot sands in the former case, 

 and Mudstone sands in the latter ; and by those limestones 

 containing thick interpolations of the same red slates (e. g. 

 Daddy-hole cove near Torquay, &c. &c.) which pass from 

 No. 3 killas into No. 4 above, and by the limestones at Shark- 

 ham point, south of Brixham, with their upper red grits and 

 schists being closely associated with, and immediately under- 

 lying, the delicate upper killas No. 4 at Man sands. 



The Dart sections describe precisely the same history of 

 events, but in simpler and more explicit terms. From near 

 Totness to Sandridge point, a nearly four-mile succession of 

 red and gray sandstones, red slates, and calcareo- arenaceous 

 gray schists (the whole at intervals showing efforts of the tiny 

 coral creatures to establish their settlements), clearly underlie 

 the limestones of Watton and Galmpton; and these in their 

 turn, along the south shore of the Galmpton creek to Green- 

 away-house and Quay ferry, as clearly underlie the upper red 

 and gray grits and coarse schists, which continue for almost 

 a mile to near Noss point, and there support the upper killas 

 No. 4, which from thence to the mouth of the Dart, and the 

 little bay west of it on the south of Stoke Fleming, overlie 

 them with a permanent high southern dip. 



* The rich and admirably-conducted mine Wheal Friendship is in the 

 floriferous or carbonaceous series below the killas. 



t This remarkable fracture was first noticed, many years since, by Sir 

 Henry De la Beche. See Geological Transactions. 



Z2 



