290 CONTRIBUTIONS TO ECONOMIC GEOLOGY, 1902. [bull. 213. 
Thicknesses of benches and partings of the Rock Creek coal. 
Location. 
Gray opening, Bertr Creek, north of Otwell. 
Proman opening, northeast of Velpen 
Rock Creek, northeast of Pikeville — 
Ilert opening, southeast of Pikeville. 
District west of Duff 
Myers opening, east of Stendal 
Hildebrand opening, east of Stendal 
District east of Zoar 
District west of Holland 
Thickness Thi k 
Inches. 
Inches. 
Thickness 
of lower 
bench. 
Inches. 
18 
24 
12 
3 
8 + 
2 
Total 
thickness 
of coal. 
Inches. 
21 
44 
24 
15 
20+ 
8 
40 
28 
24 
GEOLOGIC STRUCTURE. 
Rather pronounced local dips are occasionally found, but a careful 
tracing- of the Petersburg and Millersburg coals by outcrops, wells, 
or shafts, shows that although there are many irregularities and even 
reversals, the general dip is nearly west, the amount varying from 15 
to 40 feet, with an average of about 20 feet to the mile. As a result 
of that dip the coals disappear one after another beneath the surface 
to the west, and at the western limits of the area are from about 50 
feet, in the case of the Millersburg, to nearly 500 feet, in the case of 
the Holland coal, beneath the level of the bottom of the deepest val- 
leys. The depth of the Petersburg coal below the valley bottoms in 
the western part of the quadrangle appears to vary from 150 to about 
200 feet. 
COALS OF THE PATOKA QUADRANGLE. 
COAL AND LIGNITE IN INDIANA. 
Coal. — With one or I wo exceptions none of the coals outcropping in 
that portion of Indiana included in the Patoka quadrangle are now 
worked, even for local supply, though temporary openings have fre- 
quently been made in the past. The one mine in the area — the Oswold, 
at Princeton — gets its supply from a bed supposed to be the Peters- 
burg, reached by a shaft at a depth of about 440 feet. The coal aver- 
ages about 6 feet 6 inches in thickness. The mines working the same 
bed at Evansville are just outside the quadrangle. 
A considerable number of deep borings have been made at Prince- 
ton and elsewhere, in which coals of some thicknesses were encoun- 
tered. Some of these are given on the following table : 
