ihuidi.] LEAD, ZINC, AND FLUOKSPAK OF WESTERN KENTUCKY. 209 
wliich is usually jointed parallel with the fault plane. If this is true 
then the two fissures should unite at some distance beneath the 
surface. 
There are at least 30 faults in the district, with maximum dis- 
placements of from 400 to 1,400 feet, and traceable for distances of 
from 2 to 20 miles or more. Since many of these are connected with a 
series of subsidiary fractures and faults, whose displacement rarely 
exceeds 200 feet, they may be distinguished as the main 'faults. Of 
the subsidiary fissures, there are probably hundreds, and it is the 
belief of the writer that many of them will prove more productive, 
for equal lengths, than the veins in the main faults. 
As a rule the fault lines are practically straight, apparent slight 
deflections in the course being generally due chiefly to the dip of fault 
planes, which is usually considerable, upon the line of outcrop over 
the undulating surface. Occasionally, however, and perhaps oftener 
than the obscured surface indications now lead us to suspect, the 
faults are broken up into series arranged en echelon. The Tabb fault 
is a good example of the latter type. 
When the displacement of the strata is sufficient to bring two litho- 
logically distinct formations into juxtaposition, as, for instance, when 
the sandstones of the Coal Measures or Chester are thrown down to 
the level of the Princeton or St. Louis limestones, there is no diffi- 
culty in tracing the fault; but where the displacement is insufficient 
to produce this result very close stratigraphic comparisons are required 
to establish its presence. Indeed, the difficulties proved almost insur- 
mountable in the cases where the faults traversed the deeply weathered 
areas occupied by the St. Louis limestone. In the cases where differ- 
ent members of the Chester formation are on the two opposite sides 
of the fault plane the difficulties are not so great, since the various 
members of the Chester formation are usually distinguishable with- 
out much trouble, and the line of the fault is very commonly marked 
by protruding masses of quartzose sandstone. 
Taken as a whole, the fractures fall into at least two (and probably 
four) well-defined systems, one trending northeast, the other north- 
west. The northeasterly system is the more prominent and its frac- 
tures perhaps more generally mineralized than those of the other 
systems. When platted on a map this system of faults, on the Ken- 
tucky side of the river, presents an obscure fan-shaped arrangement, 
radiating and diverging eastwardly from the region between Salem and 
Pinckney ville, in Livingston County. The ribs of the fan pass through 
Crittenden County, and its successive lines become more and more 
easterly as we approach the southern boundary of that county and 
enter Caldwell, where they strike from a little north of east to a few 
degrees south. It is to be understood that the fan-shaped arrange- 
ment of the main fractures of this system has no known genetic rela- 
tion to the dikes of the district. No igneous rocks are known to occur 
Bull. 213—0:3 14 
