PENNSYLVANIA^ SERIES. 21 
known only from well records, and as in the great majority of cases no 
coal has been recorded below the Pittsburg, not many data are at hand 
by which to judge the intervals. A few records, however, report the 
"Connellsville" coal, which is believed to be equivalent to the Upper 
Freeport bed of the Allegheny Valley. The C. M. Reed well, in North 
Strabane Township, reports the interval as 600 feet from the top of the 
Pittsburg to the top of the Freeport. The Reed well (265), in the bor- 
ough of Washington, records the same interval as 595 feet. If 8 feet 
is allowed for the probable thickness of the Pittsburg coal, the thick- 
ness of the Conemaugh in the two wells is 592 and 587 feet, respec- 
tively. A number of wells in the gas field between Zollarsville and 
Beallsville report the Freeport coal, and the computed intervals are 
given under the heading "Coal" (pp. 88-117). 
Character. — The Conemaugh formation consists principally of alter- 
nating shale, sandstone, and sandy shale, although thin limestones and 
occasional coals are known to occur in it. In many places in south- 
western Pennsylvania it contains a number of beds of red shale of 
variable thickness. These do not occur at any regular horizon, but 
lie usually in the upper 400 feet of the formation. The Murphy and 
Little and Big Dunkard sands of the drillers, corresponding, respec- 
tively, to the Morgantown, Saltsburg, and Mahoning sandstones on 
the surface, are in this formation. Probably the most detailed sec- 
tion of the Conemaugh in the Amity quadrangle is that recorded in 
the Matilda Davis No. 2 well (29), in the borough of Deemston. 
The section is as follows: 
Section of Conemaugh formation in Matilda Davis No. 2 well, Deemston Toumship. 
Feet. 
Coal, Pittsburg. 
Lime 45 
Slate 20 
Lime 35 
Slate 13 
Lime 25 
Red rock 10 
Lime shells a 45 
Slate 10 
Lime/ 13 
Slate 5 
Lime 15 
Sand 8 
Lime 25 
Sand 25 
Lime 8 
Red rock 31 
Lime 12 
aAlmost all deep-well records contain frequent reports of such occurrences as "slate and shells," 
"sand and shells," or simply "shells." The "shells" referred to are not fossil shells of organisms, as 
in the ordinary sense of the word, but consist of alternating thin layers ("shelly layers") of shale 
or sandstone. 
