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trouble and expense to the miner by shifting the lodes 

 from their usual course, by deranging their contents, 

 and oftentimes by cutting out all their mineral riches. 

 On the other hand they are sometimes advantageous, as 

 that part of them which consists of flukan is impervious 

 to water. 



It has been shown that cross courses traverse all those 

 true veins which have been already described ; it remains 

 to be shown that they are traversed by other veins. 



There are several instances where these are crossed 

 by the more recent copper lodes ; also by cross flukans, 

 as at Huel Damsel, in the valley north of it. This valley 

 is intersected by a large cross course which is supposed 

 to run from sea to sea ; and this cross course is traversed 

 most completely by a cross flukan. The country or for- 

 mation in a part of this valley bears the marks of con- 

 vulsion, being in great disorder and confusion. The cross 

 course evidently partakes of this disorder, but the flukan 

 appears to bear no marks of it. If, therefore, there had 

 been no intersection, there would be no difficulty ia as- 

 certaining the comparative age of those two veins. Slides 

 traversing cross courses have been found, as at Poigooth 

 and other mines. 



Cross courses are in general unproductive of copper 

 or tin, but some rare instances have occurred to the con- 

 trary. Lead, arseniate of cobalt, sulphuret of antimony, 

 native silver, with oxides and sulphurets of the same 

 metal, occur most frequently. 



The more recent copper lodes, forming the sixth class^ 

 comprize the east and west and also the contra lodes, 

 which have been found to traverse not only other copper 

 lodes, but cross courses also. They are not numerous, 

 but may be seen in Huel Alfred, fig. 17, pi. 25, and the 

 Weeth, fig. 12, pi. 25. 



The veins of this class are traversed by cross flukans. 



