ULRKH] LEAD, ZINC, AND FLUORSPAR OF WESTERN KENTUCKY. 207 
Abilities. It seems probable, however, that a field containing mines 
that at various times were operated with profit for the lead ore alone, 
the zinc ores and fluorspar being left on the dump, should under 
economic and competent modern management become a producer of 
some importance. Two obstacles stand in the way at present. The 
first is a lack of a cheap and thorough method of separating the fine- 
grained sphalerite from the fluorspar with which it is almost invaria- 
bly associated. Now that the need of such a process is emphasized, 
it is possible that a satisfactory method will be discovered before the 
second impediment — lack of transportation — can be overcome. Many 
men are working on the problem and already several promising if not 
wholly satisfactory processes have been patented. A plant to do this 
work has just been completed in Paducah and another is being erected 
in St. Louis, while a third process is being perfected at a plant near 
Salem, Ky. 
The second difficulty in the way of the development of the district 
is one common to all new fields, namely, a lack of transportation 
facilities. The roads throughout the district are almost without 
exception very bad, rendering successful mining where the wagon 
haul exceeds 5 miles impossible. Fully two-thirds of the entire dis- 
trict lies more than that distance from the lines of the Illinois Central 
Railroad which traverse it. However, two navigable rivers, the Ohio 
and the Cumberland, are being used in a small way, and this cheap 
mode of shipment will doubtless exert a considerable influence on the 
development of the field. 
GEOLOGY. 
Stratigraphy. — The geologic formations exposed at the surface or 
penetrated in mining in the area under consideration are all of Car- 
boniferous age, the lowest being the St. Louis limestone of the Missis- 
sippian series, while the highest contains the two lower coal beds of the 
Coal Measures and is confined to the eastern and northern edge of the 
district. These lower Coal Measures constitute the western border of 
the western Kentucky coal basin, which extends into the district from 
the east and north. As is proved by outliers, remaining chiefly 
because they crown blocks thrown down in the faulting of the region, 
this border once extended much beyond its present limits, the basal 
Coal Measures perhaps having originally covered the whole of the 
area. The base of the Coal Measures or Pennsylvanian series is here 
always formed by a coarse brown sandstone containing more or less 
abundant quartz pebbles. Immediately beneath this come the sand- 
stones, shales, and limestones of the Chester group, the rapidly alter- 
nating beds of which have a total thickness of about GOO feet. Next 
beneath and intervening between the base of the Chester and the top 
of the St. Louis limestone is the Princeton limestone, 200 to 250 feet 
thick, which is light-gray and compact and includes more or less shale 
in its upper third, and more massive, oolitic, and light-gray or nearly 
white in its lower two-thirds. Between these two divisions of the 
