184 

 Genesis. 



Some of the earlier investigators such as Hind and Hunt, 

 maintained that the interstratified veins are syngenetic, 

 that is, were formed contemporaneously with the con- 

 taining rocks, but later students of the Nova Scotia gold 

 fields are thoroughly convinced that they are epigenetic, 

 i.e., deposited subsequently. That the cross-veins are of 

 later origin all are agreed. 



Campbell, the pioneer in the gold fields of the province, 

 expressed the opinion that the veins were of later origin 

 than the rocks, and Selwyn and Poole were strong supporters 

 of his theory. The opinion that prevails to-day is that the 

 veins were formed during the folding of the rocks, in the 

 openings produced by the movements of the strata. 

 During the folding of the interstratified beds of slate and 

 quartzite, or shale and sandstone, there was a certain 

 amount of slipping of one bed over another. This slip- 

 ping produced openings along the bedding planes, which 

 were in general widest at the apex of the folds, and decreased 

 in width with depth along the limb until at a depth of a 

 few hundred feet they pinched out. During or subsequent- 

 ly to the formation of these openings, which took place 

 within the less resistent beds, the vein filling was introduced 

 by solutions. Thus is explained the dependance of vein 

 distribution on rock structure. 



The arching of the rocks on closely folded symmetrical 

 domes produced fissures passing over the apex and down 

 each limb; on broad domes the arches were not strong 

 enough to sustain themselves and the fissures were formed 

 only on the limbs; on unsymmetrical domes the slipping 

 of the strata was such as to produce Assuring along the 

 bedding planes of the limb with the higher angle of dip; 

 and subordinate flexures, in which the strata were given 

 a curve of less radius than ordinary, were especially favour- 

 able to the production of fissures. 



The process of folding was long continued and the deposi- 

 tion of vein matter probably took place during the process. 

 Small fissures were formed along the bedding planes and 

 filled with quartz only to be followed by other parallel 

 openings between the quartz sheet and the slate and fur- 

 ther precipitation of quartz in the new openings. Films 

 of slate adhering to the quartz forming the wall of the new 

 fissure thus became embedded in the vein. A succession 



