68 [APPENDIX 



texture, where they enter the greenstone, much greater than those of 

 recent date. It is seldom found that this suite of veins has cut through 

 or in any way disturbed the slates wljich rest on the granite, even when 

 the latter are in (the immediate neighborhood ; less rare is it to find 

 them cut through by the older group ; that in a line of travel over two 

 hundred miles in length that I have seen but two instances in the east 

 ern range of veins, and it is even questionable whether this dike be 

 longed strictly to the older group. 



The effect of these veins on the rocks which they pass through, has 

 been to disorganize their structure to a considerable extent, which has 

 rendered the decomposition of both more rapid and complete, hence it 

 frequently happens that rich deposits of metal are found -in such places, 

 and usually occur near the point of contact of both series of rocks. The 

 older group is found to extend from near the summit ridge of the moun 

 tains to a distance of about forty miles toward the west, and constitute 

 nearly six-eights (6-8) of all the veins found within this line of distance, 

 and on these are located the greatest proportion of all the mines at pre 

 sent in operation. 



In that portion of the country lying north of the Cosumnes River 

 and ranging thirty miles east of the Yalley Sacramento, the central line 

 of dikes belonging to the older group, are found, their western edge 

 passes through the counties of El Dorado, Placer, Nevada, Bu'tte and 

 Shasta, and as far north as the Mt. Shata hills to the east of the peak. 

 It is well developed in the counties of El Dorado, Placer and Nevada, 

 and in one locality in the county of Yuba, a short distance above Scott's 

 Ferry. In these latter counties the more recent group is also found, and 

 in the county of Nevada it is seen to have disturbed the older groups in 

 some localities, and in Placer county, where both have features in com 

 mon which will be noticed more particularly when treating of the Eecent 

 group. 



To localize the upper and older group- of these veins, a few localities 

 will be given for the purpose of familiarizing their geographical positions ; 

 in Nevada county it is met with, at the National vein, also at German 

 Bar, at the Ariel Mine in Sierra county, and the Jamison Creek mines 

 in Butte county ; on the American forks at the Volcano mine, El Dorado 

 county; Leake Vein, Calaveras county; Big Oak Flat, and Marble 

 Springs, Tuolumne county. 



These localities are situated far into the mountains, and are situated on 

 the eastern part of this line of dikes, and upon those parts of it where 

 it is most largely developed, becoming an extended and well defined con 

 tinuous range. 



Keturning to the middle or central range of dikes, at the distance of 

 thirty miles from the valley, and travelling south we find that immedi 

 ately after crossing the Consumnes, the granitic rocks that have hereto 

 fore been found associated with this range of veins further north begin 

 to disappear in a gradual manner, and the prevailing rocks are talcose, 

 to the exclusion of almost every other of the primitive series ; for a dis 

 tance of about fifty miles, the quartz is found associated with this or some 

 of its- subordinate members, the granitic rocks lying far to the east. The 

 quartz vein found among the talcose series and which appear of the same 

 age as those occurring in the grange, are equally uniform in the general 



