Geology of the DlaiHond Creek Area. 3-J'.> 



discission, Imt they are a combination of both. It is also fairly 

 certain that the fissures in some places have l)een enlarged by 

 metasomatic replacement. Absence of crustification, the dense 

 character of the quartz, and irregular inclusions 61 dyke material, 

 probably undigested portions, suggest this. 



(2) Fissures in which the bedded reefs occur. The origin of tliesc 

 has previously been suggested as due to movements connected ■with 

 the folding of the sediments. The correspondence of these reefs in 

 dip and strike with the silurian also supports sncli an origin. 

 Movement on a minor scale has taken place along the bedding 

 before the formation of these reefs as noted al)ove. Occasionally 

 slipping has occurred along the bedding, although no reefs are 

 present. 



9. — Origin of the Gold Bearing Solutions. 



One or two points bearing on tliis discussion might be first 

 noted : — 



(1) The close association of the c^uartz veins with the dyke sug- 

 gests strongly some genetic relationship between them. 



(2) The nature of the minerals formed in the dyke due to the 

 alteration. These minerals have been shown ;ii)ove to be those that 

 are formed by juvenile solutions rather than by vadose ones. Pyrite, 

 for instance, is generally decomposed by the vadose waters, but is 

 frequently formed by either upwai-d or downward moving thermal 

 waters. 



(o) Assays of the pyrites and of the dyke have been made at 

 various times to see whether it would jjay to treat the proposition 

 as a low grade one. Very little gold was found to occur in the 

 pyrites, and still less in the dyke. It might be suggested tliat tlie 

 gold originally occurred disseminated through tlie dyke, and that 

 it was transferred to the veins by a jjrocess of lateral secretion. The 

 assays shov.'. iiowevei', very little guld in the dyke away from the 

 mineral veins, and such a transference as suggested above dovs not 

 seem likely to have occurred. The presence of stibnite in both 

 the dyke and in tlie (piai'tz veins suggests that tlie solutions which 

 caused the alteration of the dyk(?, and those which introduced the 

 gold were of similar origin. The fact that the Dry Creek 'dyke, 

 wliicli has l)een very little altered, contains very little gold, ^ issti'ong 

 evidence in support of the view that the solutions which brought the 

 gold into its present position were a final phase of the same 

 solutions that caused the alteration of the dyke. The writer pic- 



1 Cf. Oregon . Memoir Oeol. Siirv. Vict., No. 3, IftO.T, j>. lU. 



