49 



been disturbed by the same agents which have disturbed the slates ; this bed of 

 the primitive group extends in a northerly direction about six miles, and is flanked 

 on the west by the sienites and granites, and on the east by the older trap rocks. 

 Among these serpentine rocks are frequently to be seen small veins and also large 

 dikes of auriferous quartz running parallel, which will be seen from their course to 

 correspond in trend with those of the more southern part of the State, and this 

 general characteristic belonging to these latter rocks (the quartz) was found to pre 

 vail as far north as my observations extended. 



Nearly all the quartz dikes of this part of the State are situated in the serpen 

 tine rocks, and it is rather an exception than otherwise, to find them associated with 

 other series of veins of any considerable magnitude. There are but very few excep 

 tions to this rule, and when these dikes are found to occur in other rocks, the 

 investing walls are usually granite. The predominance of these veins among the class 

 of rocks alluded to, fixes to a certain extent their probable age, and like the dikes 

 of the counties of Nevada and Amidor, come under the classification of former 

 reports in which they have been arranged as primitive, in order to separate them 

 from a class similar in constitution, which appear to have been intruded subse 

 quent to the deposition of the slates. 



Up to the present time, there have not been observed any extensive quartz 

 ranges which have the appearance of having protruded through the slate formation 

 of this part of the State. I have heard of two localities of this character, one of 

 which I have subsequently visited, but found on examination that the Slate 

 belonged to th stratified rocks of the primitive series, and were almost exclusively 

 talcohe schist. In those localities where opportunities occurred for the examina 

 tion of the trapean rocks which were found adjacent to these dikes, they presented 

 the same appearance and evidences of having broken through that class of rocks. 



This is manifest in nearly every vein to be met with for the distance of five or 

 six miles from Shasta City, and is particularly well defined in the vicinity of 

 what is known as the Quartz Mountain, eight miles north-east of the town and 

 on the head of the Sacramento Valley. From this brief outline of their gener 

 al features and associations, it is difficult to form any other conclusions than those 

 at which we have above arrived, respecting their strictly primitive character ; 

 and as such, when found to be auriferous, they are discovered to be equally val 

 uable with those in other parts of the State. In traveling north-west of the 

 town, and well on to Tower's Bridge we find a diminution in the outcrop of these 

 rocks, but after crossing Clear Creek and assuming a more northerly course they 

 again make their appearance in well defined lodes running parallel with each 

 other for long distances. The best position for examining their relations 

 with the adjacent rocks is three miles from Frenchtown at the Mt. Washington. 

 Mine. At this locality the parallelism of the dikes is observable along the flanks, 

 and over the hill on which this mine is situated. A level has been driven about 

 200 feet on the main lode of the mine, which has exposed the walls of the vein 

 for that distance and at a vertical depth of about 150 feet below the outcrop. 

 It is here found that the lode traverses the primitive rocks exclusively, and like 

 the other mines in the State the power of the lode is increased as it descends. 

 In the vicinity of the reduction works of this establishment are large masses of 

 an amygdaloidal trap, which is found in situ a short distance west of the build 

 ings. This rock is cut through in every conceivable direction by small threads 

 of quartz, which I have found to contain gold, showing most conclusively that 

 the mineral was injected at a subsequent period to the formation of this trapean 

 mass. 



In traveling up the canon from the bridge above alluded to, the quartz dikes 

 are found to crop on the sides of many of the hills as we pass along ; as the 

 ascent of the Trinity ridge is made from McLaughlin's ranch, which is situated 



