282 ASSINN1B0INE AND SASKATCHEWAN EXPEDITION. 



of about 10,000 feet. He has shown the occurrence, 

 after the irruption of the interstratifled greenstones, of 

 two systems of trap dykes, and a third of granite, inter- 

 mediate in time between the two irruptions of trap. The 

 formation of the metalliferous veins is still more recent. 

 The principal mineral species of these veins are native 

 copper, quartz, calc-spar, dolomite, fluor, and sulphate of 

 baryta, with several zeolites, of which laumonite is the 

 most common, heulandite, stilbite, thompsonite, apophyllite 

 and analcime are also met with, as well as prehnite and 

 datholite. These veins are only metalliferous where they 

 traverse the beds of greenstones." 



