110 GEOLOGY OF OHIO. 
Ft. In. 
Cambridge limestone at top of Rich Hollow Hill ......................068 5 
Tntervalirosccccccccoscsccrccsserscecseetssorcusocceeuereeccset teceeaeeeenee ... 132 
Upper Freeport limestone—Shawnee limestone ....... BA OHEONCOE RESETS = 
Tri terval cies case scsc eee cnetedesusadeceacaccoecedantacuces se umseceadacmemeementees 76 
Middle Kittanning Coal—Mineral City and Carbondale seam.... 3 6 
EMGORVallcccs..c.ccccccnccs'escosceceessescssccssemneteeteecevecssoetescnseeneceteers 27 
Tbaunap IGE EO (COI, (OSI @)))o06 0005-73000 660'50000000000006000000000000000000 1 
Keittanmingiclayacccs--scot.csscccccanstecsesccersccoeect eset enemeneecener ener 10 
Ferriferous limestone and ore, both formerly worked ................«. 2 6 
IMGOTV Al eS oeccss st ossccosscpeeseccnvececncss semeeetce stone eens iemsmemenc eae ates 14 
TRON ORs WOVRONETARY VFO ELS 8hs0500009000000600000000600000000000000000000000 1 
TMtOrval istics. ipstectcsccsodesesccsesncsdsescceccsscoscese stan soetuerseceeneetcee 34 
Coal—Tionesta (?) No. 3b, overlain by black slate..............0..000 2 
Umberviall os is.cs ah se ie ces domes nee seeaeeowsctece ch oc tne teslectee coteeectene reece eee ees 16 
OnE Ooy ere WNEIREETE, INIOs Bioc0000000 0900905000000000000080000000000000000000 eG 
TNMGOV VAL. tcc. ceecccstecseotseses ousllancsllensisme Nees ane secencta te meectoeeneeeeeacs 21 
‘Lower: Mercer limestone secvccnco) Soc sie ec ue teen cena eee ee ees 5 
Ibignap WER (Ooeth ENGL EWES ISIC 335605060060 508000000000005000000000000000 7 
There is not a clearer section in the Ohio Coal Measures than this. 
It has the four limestones that are most serviceable in carrying horizons 
from point to point. The Lower Mercer limestone in particular is in 
its best and most characteristic development. It lies in the bank of 
Raccoon Creek, and covers quite a heavy deposit of interstratified coal 
and slate, which is of little or no value. The limestone soon rises from 
the banks of the stream to the westward, and is found everywhere at 
its proper level. If there is any one formation that every one knows, 
and about which no controversy is possible, it is the Lower Mercer or 
Blue limestone. Various attempts have been made to mine the coal 
below it to the westward, but aside from small county banks, it sup- 
plies no proper basis for mining. 
The Ferriferous or Gray limestone is here seen at its extreme 
eastern development. Everywhere to the west and south it is in full 
force, and its ore has been thus far the chief mineral element of value 
throughout this region. It was first recognized, though somewhat 
doubtfully, by Andrews in his report of 1870, but the section in which 
it occurs is in all respects normal, as I have shown in vol. III, p. 922. 
The Cambridge limestone, in like manner, is unmistakable. There 
is no stratum with which it is in danger of being confounded. In the 
present section it is 212 feet above the Carbondale coal, and this measure- 
ment certainly forbids the reference of this seam to any higher horizon than 
