306 ORIGIN AND DEVELOPMENT OF ORE-DEPOSITS. 



not be found after, although a good sum was expended in search 



of it the lode was never found under the elvan," The 



same elvan passes on to Q-reat Wheal Fortune, where it heaves 

 the lode and branches. At Q-reat Wheal Vor, according to the 

 same author, the elvans pass through the tin lodes without 

 heaving them. Another elvan similarly heaves the No. 2 tin 

 lode, at New Hendra Mine, in the same parish. 



Class II. — Faults of the Granite Junctions. 

 The maps of the Geological Survey shew the various granite 

 masses as if bounded in general by curves, with the stratified 

 rocks bending round them. This is no doubt correct in many 

 instances, but a close study of these junctions, as seen in mines, 

 quarries, sea-cliffs, road-cuttings, and the like, shows that in 

 many places at any rate the junctions consist of fault-planes 

 which have little or no relation to the strike of the slates and 

 schists. It is true that the granite often sends off veins into the 

 slate, especially, perhaps, where its strike forms a considerable 

 angle with the general line of junction. It is true, too, that the 

 slates are generally elevated considerably around the various 

 granite masses, movements having taken place when both 

 granite and slate were so far beneath the present surface 

 as to be in a soft or pasty condition. Subsequent movements 

 of elevation appear to have taken place along lines of fault, as 

 at Cligga, Ponsanooth, Carclaze, and many other places, and 

 some of the displacements are of considerable extent, as was 

 formerly to be seen on the south side of Carclaze clay-pit. The 

 granite itself, in the neighbourhood of these junction faults, is 

 very much kaolinized, and more or less permeated with schorl 

 or even converted into schorl-rock. This rock frequently contains 

 disseminated particles of tin, although the fissures themselves 

 contain too little tin to be reckoned as tin lodes. The adjoining 

 slates are also highly metamorphosed, sometimes, and particularly 

 around Dartmoor, into andalusite schist — more often into 

 " spotted killas " filled with incipient crystals of andalusite, 

 D-arnet or other minerals, — sometimes into a wrinkled micaceous 

 schist and in the centre and West of Cornwall, very commonly 

 into true tourmaline schist, as at Carclaze HiU, Cligga, the flanks 

 of Cam Marth above Ting Tang, Wheal Vor, and many other 

 places. 



