i«3 



The observation of these and numerous other relations 

 led the writer to the propounding of the "pay-zone " theory* 

 As has been pointed out the distribution of ore-shoots is 

 dependent on the structure of the anticlinal fold or sub- 

 ordinate flexures on the fold: they lie in a line passing 

 through similarly curved or twisted portions of the strata 

 that during the folding process were subjected to pressures 

 and tensions and were fractured so as to permit the trans- 

 mission and deposition of minerals. The subordinate 

 flexures and peculiarities of structure, on which the dis- 

 tribution of ore-shoots depends, extend to an unknown 

 depth, and it is claimed that interbedded veins and 

 ore-shoots should succeed one another with depth so long 

 as the same structural conditions continue as at the 

 surface. These structural conditions generally extend 

 in depth parallel to the axial plane of the dome. We thus 

 get a pay-zone the surface extent of which coincides with 

 the surface over which the ore-shoots outcrop and which 

 extends parallel with the axial plane of the dome to an 

 indefinite depth. 



The evidences in favour of the theory are the fact that 

 gold mining has been carried on in the province to a 

 vertical depth of 1,000 feet (300 m.) in fissure veins and 

 900 feet (275 m.) in one interbedded vein; that pay-ore 

 is not limited to any particular horizon, but has been mined 

 throughout the whole thickness of the Goldenville forma- 

 tion; and the analogy existing between the interbedded 

 veins of Nova Scotia and the saddle-reefs of Bendigo, 

 which have been worked successfully to a depth of over 

 3,000 feet (900 m.) and proved auriferous at over 5,000 

 feet (1,525 m.). 



While the hypothesis may be of general application it is 

 not claimed that it will hold in all particular cases. Struc- 

 tural features vary with depth; subordinate folds may 

 not persist and main folds may flatten and thus the pay- 

 zone may die out or be shifted in position with regard 

 to the anticlinal axis. For example, in the case of the 

 Dufferin mine, rich ore was found at the apex of the fold 

 at the surface, but in the underlying veins owing to the 

 flattering of the dome it was more remote from it. 



*Geol. Surv. Can., Vol. V. p. 57 A. A. and Vol. X. p. 10S A. 



