53 



The situation of these rocks is such that water power may be used almost 

 directly upon the ground from which they are extracted, from the current of a 

 small stream, the tributary of a creek which flows directly to the east of one of 

 the main ledges, and carries water throughout the year. With these advanta 

 ges, and the character of the rocks combined, it is to be hoped that attention 

 may be turned to this department of trade, and thus add another to the list of 

 our available resources. 



TRINITY COUNTY. 



The southern and south-eastern line of this county is separated from that of 

 Shasta by the high ridge known familiarly as the Trinity Mountains. These at- 

 tain an elevation of about 4000 feet, at the points at which the trail crosses this 

 ridge. There are but few points along the line of travel that exceed this height; 

 it may therefore be considered very nearly the general mean altitude of this 

 range, or rather spur of the coast mountains. The rocks composing this ridge, 

 are granite and sienite, deeply underlaid by the greenstone trap which descends 

 to the beds of the streams, and forms the principal led rock of the placers of 

 this section. On the flanks and near the base of the ridge, there are frequently 

 to be met with, isolated masses of the metamorphic rocks, the chief of which 

 are slates. These rocks often present a porphyritic structure, especially when found 

 in contact with the trapean rocks, or with quartz. 



I do not remember one instance in which the sedimentary rocks were found 

 in an altered condition, when in contact either with the granite, the sienite, or 

 any other member of that cotemporaneous group alone. I therefore infer that 

 they were deposited upon the latter subsequently to their consolidation, and any 

 changes which they may have undergone since their deposition and uplift, are 

 occasioned by the intrusions of more recent igneous rocks, which have alike dis 

 turbed the slates, and the primary rocks on which they rest. In using the word 

 primary in this case, it is applicable to the granitic series, including the serpen 

 tines, and is intended to separate the series of this part of the State, from rocks 

 of identical constitution in other localities, which are beyond question, not older 

 than some of the lower members of the tertiary era. These latter rocks were 

 merely alluded to in my first report to the Legislature, and will be found thus 

 noticed on the 12th and 13th pages of that report. 



The deposits of placer gold found in these districts lie superior in position to 

 the metamorphic series, and also superior to most of the slates. It is usually 

 found imbedded in the gravel drift, which is composed for the most part, of 

 rolled masses of the primitive group, almost unmixed with any other of the ad 

 jacent rocks. The entire district west of this range exhibits the marks of old 

 water lines, from which the waters have since receded, the outlet being probably 

 through the Klamath to the ocean. The waters were apparently fresh, and the 

 drift beds and clays which formed the bottom are charged with large quantities 

 of vegetable remains ; but as yet no relics of animals have been found. 



The small amount of deposits found among the drift, and belonging to the 

 more recent rocks leads naturally to the inference that the gold deposits of these 

 basins were derived mostly from the primary suites, and such was subsequently 

 found to be the fact on examining the geological relations of the rocks found 

 among the mountains. This characteristic was prevalent as far as the crossing 

 of the Scott River mountains, and westerly for a distance of not less than 40 

 miles. In this place we shall resume the consideration of the quartz veins and 



