92 TJie Americofi Geologist. Febmary, i90(» 
pentine, midway between the Lawrence and Keating faults, shearing 
along a line of faulting has produced a seam or belt of talc and ser- 
pentine schists, 40 feet in width. This carries gold in paying quan- 
tities from wall to wall, while in places the greenish-gray crushed 
schist is rich to the extent of $2,000 per ton. A dike of dark green 
dioryte-porphyryte of the earlier system is involved in the crushed 
belt, but passes obliquely out of it and evidently has had nothing to 
do with the presence of the gold. In the neighborhood of the main 
talc belt of the Blue Lead-Iowa, the serpentine is seamed by similar 
streaks of schistose material and they invariably "prospect" in free 
gold. 
On the adjoining Red Swan claim, gold is found in talcose schist, 
in narrow gouges in the massive serpentine, in veinlets of chrysotile. 
and in a dike of quartz-porphyryte similar to that of the Hardscrabble 
mine. In this case also, the white quartzyte-like dike abounds in 
oxide of manganese (locally known as ""soot") in cracks and in cav- 
ities averaging several cubic inches in contents. A dike of dioryte- 
porphyryte of the later system cuts this quartz-porphyryte dike near 
the point where the latter appears to be richest in gold. 
Discussion . 
It is itniversally asked of all new districts. "Will the mines 
go down?" An intelligent reply to this question while the dis- 
trict is yet in an incipient stage of development, requires some 
knowledge of the source from which the gold in the veins was 
originally derived. As evidence tending to the solution of this 
problem, for the Upper Coffee creek district, I wish to present 
the following: 
1. The close association of the mineral belt with the two 
prominent faults (Keating and Lawrence) suggests that its ex- 
istence was largely dependent upon these great breaks in the 
strata. All the richest gold districts of northwestern California 
(except those characterized by the "pocket" deposits), are con- 
nected with great faults. The planes of these faulted fissures 
are invariably nearly vertical, and hence the faults must de- 
scend to profound depths within the earth's crustal zone. 
2. The so-called "ledges" of the Upper Coffee creek district 
are faults, which may or may not carr\' a vein of quartz. The 
shearing action along the contact of the moving walls, has 
converted the country-rock into schists, forming belts from 2 
io 40 feet in width. By metasomatic action, a further modifica- 
tion has occurred, the serpentine schists being converted into 
talc and allied minerals. I want to emphasize the fact that even 
