ransome.] INTERSECTIONS AND RELATIVE AGES OF FISSURES. 57 
many of the fissures intersecting nearly at right angles (conjugate 
fissures) were produced by a single principal stress. In the greater 
number of instances, however, in which lodes are known to intersect, 
the exposures are such as leave the actual character of the crossing 
and the relative ages of the fissures in doubt. They may or may not 
have been simultaneously formed. 
Fairly clear evidence of the intersection of an earlier vein-filled 
fissure by a later one without recognizable faulting was obtained at 
several points. The prominent lode outcropping along the crest of 
Green Mountain crosses and is distinctly younger than a strong vein 
of barren quartz, aboul 10 ted wide, which is accompanied by several 
parallel minor veins and strikes about N. 60° E., dipping 80° to 85° 
southeasterly. The younger Lode has a general strike of about X. 30° 
W. and a steep southwesterly dip. The intersection is thus approxi- 
mately rectangular, and is not accompanied by faulting, so far as 
could be seen. In the complex network of Galena Mountain it was 
found thai al least one of the several tiorth-and-south veins was cut 
by at least one of the numerous veins striking nearly X. 25° W., and 
those in turn are apparent^ intersected in several instances by lodes 
trending about N. 65 W. One of the latter was also observed to cut 
a lode striking aboul \. 30 E. In none of the cases mentioned was 
the intersection accompanied by visible results of faulting. Other 
probable examples of northwesl lodes cutting northeast lodes occur 
on Treasure Mountain, but the exposures were not such as to place 
the question of relative age beyond doubt. 
The shaft of the San Juan Chief mine was sunk at the crossing of 
two lodes, but it is by no means clear that they are of different age. 
The main lode, striking about N. -40° E., formerly produced some ore 
from surface workings. The fad thai in their underground develop- 
ment the owners of the mine appear to have inadvertently drifted 
along the barren intersecting lode, striking about X. 60° E., is the 
only indication that the latter may be younger. 
In three places only were lodes found to be faulted by later trans- 
verse vein-filled fissures. The King lode, in Cataract Gulch, 2 miles 
south of Silverton, with a strike of N. 6' W. and a dip of about 80° 
to the west, is faulted by a small approximate^ east-and-west quartz 
vein, dipping south at about 50°. By this faulting the northern portion 
of the King lode is thrown about 12 feet to the westward. In the 
Silver Lake mine the important Xew York City vein, with an average 
strike of about X. 20° W., and dipping generally northeast at about 
80°, is cut by a faulting lode, which, where best exposed, is a breccia 
zone about feet wide, composed of sharply angular fragments of 
country rock cemented by quartz carrying a little worthless ore. 
This fault tissure strikes apparently about X. 73° E. and dips about 
75° to the south. The Xew York City vein is displaced in the same 
way and to about the same degree as the King lode. In the Ridgway 
