324 GEOLOGY AND GOLD DEPOSITS OF THE CRIPPLE CREEK DISTRICT. 
dike, or Mary McKinney “flat vein.” This strikes approximately northwest and 
southeast, and dips southwest at an average angle of 20°, which is about the same 
as the slope of Gold Hill. It is cut in the Burke and Fry shaft 400 feet below the 
surface. On level 3 it appears about 50 feet north of this shaft, in the breccia. It 
is here about 4 feet in thickness and has a higher dip than usual. Toward the 
north it passes about 75 feet above the Ophelia tunnel at the point where the latter 
cuts what is known as the No. 2 vein of the Mary McKinney mine. The basic sill 
exposed in the Ophelia tunnel about 3,900 feet from the portal is probably the 
same as that known in the Mary McKinney mine. The more conspicuous sill 
exposed from 4,600 feet to 4,800 feet in from the portal is apparently a second 
and lower sheet of “basalt” which seems not to have been encountered as yet in 
the Mary McKinney workings. On level 4 of the Mary McKinney the Howard 
sill occurs about 200 feet south of the Burke and Fry shaft and is here in phonolite. 
It is about 3 feet thick on this level. On level 5 the trachydolerite is cut about 
425 feet south of the Burke and Fry shaft, and has been followed for over 300 feet 
in a curved drift. Here also it is in phonolite. A general idea of the geological 
relations in the Mary McKinney mine maybe had from fig. 32 (p. 323), which is a 
map of level 4. 
LODE SYSTEMS. 
The horizontal relations of the principal lodes are shown in fig. 32. On all 
the levels the Mary McKinney lode maintains its usual regularity from near the 
south end of the property to within about 200 feet from the contact between the 
phonolite and breccia, in the northern part of the mine. South of the shaft the 
lode strikes N. 9° E. North of the shaft, however, it curves gently eastward until 
it strikes N. 25° E. The dip is westerly and ranges from 65° to 75°. 
The Le Clair is a vertical lode, striking N. 6° E., and intersecting the Mary 
McKinney lode at an acute angle. On level 2 the crossing of the two lodes is well 
shown and is about 200 feet south of the shaft. Neither lode appears to displace 
the other at the crossing, nor is there any indication of one lode being older than 
the other. On level 3 the intersection occurs about 100 feet south of the shaft. 
On level 4 the lodes cross about 275 feet north of the shaft, but continue close 
together and apparently coalesce near the shaft. At 175 feet south of the shaft a 
fissure zone turns off to the south and has been followed for over 100 feet in a 
drift. This is probably the Le Clair. If so, the two lodes practically coincide on 
this level for a distance of over 400 feet. On level 5 the Mary McKinney and 
Le Clair lodes join 375 feet north of the shaft, run together for about 100 feet, and 
then gradually diverge. They appear to meet again near the shaft. South of the 
shaft on this level the Le Clair is unknown. It has been explored for a total length 
of about 1,000 feet. At several points the Mar}^ McKinney lode is crossed at 
acute angles by other fissures similar to the Le Clair, but of less persistency and 
carrying much smaller values. 
In the southern part of the mine these two lodes are the only ones of economic 
importance. In the northern part, however, the Assuring, as already stated, 
becomes more complex, as may be seen from fig. 32 (p. 323). As the Mary McKin¬ 
ney lode is followed north it shows a tendency to split up near the contact between 
