ORIGIN AND DEVELOPMENT OF ORE-DEPOSITB. 286 



For many years the classification of the Cornish mineral 

 veins as regards age, has remained pretty much as Mr. Carne 

 left it, and even now there is very little to correct in his statement 

 except perhaps his too sharp distinction between " copper lodes " 

 and "tin lodes" and the classing of the Elvan courses as 

 " doubtful veins." But I think it may be shewn that including 

 his eight sets of mineral veins and some others since recognized, 

 at least 15 (or perhaps 16) distinct systems of fissures, all ore- 

 bearing to some extent (except perhaps Nos. 14 and 15) have 

 been produced in the district in post-carboniferous times. It is 

 highly probable that there has been motion of the rocks at 

 greatly more than 15 distinct epochs, probably no long time has 

 ever elapsed without some movements, but of these fifteen sets 

 of movements, there are still abundant traces visible. The 

 following are the systems referred to : — 



1 . — Older Elvan faults. 



2. — Faults of the Or anite junctions. 



3. — Oldest Tin lodes. 



4. — Newer Elvan faults. 



5. — Older Tin lodes. 



6. — Newer Tin lodes, 



7. — Oldest E. W. Tin and Copper lodes. 



8. — Older Gaunter Copper lodes. 



9. — Older Cross-courses. 

 10. — Newer E.W. Copper lodes. 

 11.' — Newer Gaunter s. 

 ] 2. — Newest E. W. Tin and Copper lodes. 

 13. — Newest Cross-courses and Flucans. 

 14. — Newest Flucans and Slides. 

 15. — Alluvial faults. 



In each case it is of course the first opening of the fissure 

 which is adopted as a basis of classification. There is good 

 reason to believe that very few, if any, of these fractures have 

 been unaccompanied by faulting, although in some instances 

 the displacements have certainly been very small, while in others 

 favourable opportunities of viewing the actual intersections have 



