NORTHERN AND WESTERN OUTCROP IN OHIO 77 



of the state, and, at a somewhat later date, Dr I. C. White followed 

 the Pennsylvania section into the county, so that the relations are now 

 sufficiently clear. The Homewood sandstone quickly becomes obscure 

 west from the state line, but the Mercer group is characteristic through- 

 out, both of the limestones as well as the coal beds being present at Lowell- 

 ville, where the Tionesta coal bed is shown at from 2 to 10 feet above the 

 Upper Mercer limestone. The Mercer group is about 70 feet thick. The 

 Sharon coal bed appears about 2 miles farther up the Mahoning river, 

 and thence in this as well as in the adjoining counties it occurs with its 

 accustomed irregularity and uncertainty. The Ferriferous limestone, so 

 important as a guide in Pennsylvania, disappears soon after crossing the 

 state line, but its office is assumed by a new limestone, very near the 

 bottom of the Allegheny formation, the Putnam Hill or gray limestone, 

 which overlies a coal bed thought by Professor Orton to be the Brook- 

 ville of the Pennsylvania column. This limestone first appears near 

 Youngstown, a few miles west from the state line, where it is 2 feet 7 

 inches thick and 36 feet above the Upper Mercer limestone. 



The Connoquenessing sandstones, termed by Newberry the Massillon 

 (which name is retained in the later Ohio reports by Orton), appear in 

 White's sections as well as in those by Newberry, and are persistent in 

 this county, though, as in Pennsylvania, they are variable. Doctor New- 

 berry's Youngstown section shows them distinct, yet in the Foster shaft 

 there they are one, with a thickness of 146 feet. Evidently several valleys 

 existed in this immediate neighborhood at one time during the Potts- 

 ville, for at a mile east from Youngstown there are barely 11 feet of sand- 

 stone in the whole Connoquenessing interval, while in another shaft, a 

 mile farther southeast, the sandstone is 80 feet. A similar condition 

 exists near Austintown, west from Youngstown, where one shaft shows 

 the sandstone continuous and 120 feet thick, whereas in most of the 

 others the sandstones are distinct and separated by the Quakertown 

 shale. The Quakertown coal bed seems to be persistent at 50 to 80 feet 

 above the Sharon, except where cut out by the overlying sandstone. The 

 Connoquenessing sandstone often replaces the Sharon shales, and at times 

 even the coal bed itself. There is little trace of the Sharon sandstone in 

 this county. The peculiarities of the Sharon coal and of its occurrence 

 have been described well by Doctor Newberry, and they will be discussed 

 in another connection.* 



The Pottsville extends northward into the southern part of Trumbull 

 county, where the exposed section reaches to the blue or Lower Mercer 



* J. S. Newberry : Report of the Geol. Survey of Ohio, vol. iii, 1878, pp. 784-795, 800, 803, 804, 805. 

 I. C. White : (Q 2), pp. 219-224, 288. 



XI— Bull. Geol. Soc. Am., Vol. 15, 1903 



