ORIGIN AND DEVELOPMENT OF ORE-DEPOSITS. 295 



Another runs 10** to 15° W. of N. through the western part 

 of Wheal Franco — it does not appear to heave the elvan. 



The next two pass through Tavistock ; the seventh has been 

 traced from Down House farm, half-a-mile west of Tavistock to 

 the Virtuous Lady mine, — a distance of three miles, — its course 

 is about 22° W. of N. 



The eighth has the same bearing, it extends from Mill Hill 

 Slate Quarry to Morwell Downs, through several mines now 

 abandoned. 



The ninth and tenth bear 35° W. of N., from Greenaver 

 Wood to Rumley, |-miles S.E. from Calstock. 



The eleventh is 5° to 10° W. of N. — it passes from IJ-miles 

 above Calstock to the Tamar, near Hall's Hole — a distance of 

 over 4 miles. Its prolongation passes right down the valley of 

 the Tamar past Saltash. It has been worked extensively in 

 several places for lead — notably at the Beeralston mines. 



The twelfth is parallel to the eleventh, and about half-a- 

 mile to the westward — it has also been worked for lead. Its 

 prolongation corresponds with an important reach of the Tamar. 



About a mile farther west is Grunnislake Glitters copper 

 mine, where the "groat" cross-course running almost exactly 

 N.S. and dipping westward, heaves the lode several fathoms to 

 the left. It is accompanied by several minor parallel courses of 

 similar bearings, which similarly affect the lode. 



Still proceeding westward we pass over a band of three or 

 four miles, in which no notable cross-veins have been discovered, 

 after which we arrive at the group of Holmbush, Kelly Bray, 

 and Redmoor, a little to the west of Kit Hill. 



The most important member of the group is that which 

 passes through Holmbush and Redmoor mines. It runs a little 

 E. of N., underlies W., cuts through Johnson's lode, the great 

 Grozzan lode, and Trelease's lode. The heaves are very slight 

 except in the case of Johnson's (underlying S.) which at the 20 

 and 30 is heaved 5 feet to the left. This cross-course has been 

 worked for lead, and in one place about 120 fathoms deep, where 

 the writer saw it in the Holmbush mine in the year 1892 ; it 

 consists of a mass of siliceous breccia in which galena forms the 



