FINENESS OF THE GOLD. 255 



The gold appears to be derived from the decomposition of tlie slates 

 and quartzites, as well as from the denudation of the quartz ledges travers- 

 ing these rocks. The source of supply of the gold is inmiense. The side 

 valleys and gulches are often excavated for miles along the outcrops of tlie 

 gold-bearing slates, and the quartzites, with their inclosed veins, have acted 

 as feeders to the placers of the main valley. Over a very extensive area 

 these rocks have been enormously eroded and the resulting material swept 

 away. The gold it originally contained has been partly caught and 

 retained in the gulches; the rest, intermixed with gravel and bowlders 

 from the metamorphic rocks, and also from the limestone and recent forma- 

 tions in the foothills, being carried far out on the plains and scattered 

 broadcast over their surface, so that very little can be ever recovered. 

 From the results of the prospecting done in this district up to August 1, 

 1875, when I left the gulch, it would be inferred that the character of the 

 bed-rock strongly influenced the deposition of the gold. Where the bed- 

 rock was a hard, massive quartzite, the water had worn it smooth, and no 

 gold was to be found on its surface, while the gravel above it was loose and 

 poor in the precious metal ; but where the bed-rock was soft, easily decom- 

 posing slates, it had caught and retained the gold swept over its surface by 

 the stream, and the gravel above, compact from the clay produced by its 

 decay, was also rich in gold. In the flats and creek bed, when a stratum 

 of soft slates is found crossing the gulch below, a high and hard bar with 

 valuable deposits should be sought for. 



In discussing the area drained by the headwaters of this stream, the 

 characteristics of the schistose rocks covering that section have been 

 already given. The main valley of the creek is excavated wholly in the 

 rocks of the second division of the Archaean, the slate and quartzite 

 formation extending- as a belt fifteen miles in width from the granite on 

 the eastern slope of the Harney Peak range to the northern part of the 

 Hills near Crow Peak. On Spring Creek the general strike of the strata is 

 northwest and southeast, with a dij) from northeast 60° to vertical, while 

 locally the rocks are seen dipping west at high angles. The rocks of this 

 formation are altered sediments, consisting of hard, massive gray or brown 

 quartzites, lamellar quartz-slates, and soft clay-slates. By metamorphic 



