294 ORIGIN AND DEVELOPMENT OF 0EE-DEP08ITS. 



N. of W., parallel to the Bovey River. It is quite possible that 

 these are of later origin than the Teign Valley lode, but they 

 may be provisionally placed in the same class. 



Proceeding westward, another galena-bearing cross-course, 

 having a very similar bearing, has been traced for a distance of 

 several miles at Holestock, near Belstone Consols, on the north 

 of Dartmoor. Two miles further to the west, still another 

 crosses Okehampton Park in a N.E. direction. 



Still proceeding westward, in the trough between Dartmoor 

 and Kingston Downs we meet with a very important group of 

 cross-courses. Within a distance of not more than seven miles 

 there are no fewer than ten or eleven great fault fissures besides 

 a considerable number of smaller ones. These fissures are of 

 two, if not three, different ages, and run in as many different 

 directions. All are, however, included within an angle of about 

 45^, from 10" E. of N. to 35° W. of N.* The once famous lead" 

 lodes of Beeralston belong to this series, their course is a few 

 degress W. of N. 



The most easterly of this group is first seen at Wheal 

 Reform, one mile east of Lydford, it cuts through the western 

 part of Wheal Betsy and Wheal Friendship in a direction 5° to 

 10** E. of N., underlying W. Another which accompanies it 

 has a course about 20"^ W. of N., it passes between that just 

 mentioned and the town of Lydford. A very important cross- 

 course occurs a little farther to the west, whose course is about 

 22 W. of N. It is first seen at Blackdown, and passes southward 

 through Mary Tavy and Burford to Penycombe Creek, a distance 

 of over four miles. It has a companion about half-a-mile to the 

 east, which passes just E. of Petertavy and forms Wheal 

 Friendship great cross-course. 



Another, more to the west, has a similar course, passing 

 through the eastern part of Wheal Franco. In cutting through 

 the great elvan course which lies to the north of the mine it 

 heaves it about a quarter of a mile to the right. 



*" Cross-courses are very numerous, and their heaves rather considerable ; at 

 Wheal Betsy and Redmoor, which are both in slate, they have yielded large 

 quantities of Galena mixed with carbonate of iron." Hen wood, Trans. E.G.S.C., 

 V, p. 139. 



