Frank Carney 
138 
walls; its presence is also indicated by a line of springs, a feature 
discussed more in detail in another part of this report* 
The Black Hand, along both vertical and horizontal lines, is 
variable in texture, grading from thin fine sandy beds to heavier 
horizons, frequently quite coarse. 
Logan formation. As one ascends from the valley floor along 
any of the roads leading to the uplands he generally notes first a 
sharp grade marking the horizon of the Black Hand formation, 
then gentler slopes which mark the horizon of the Logan sand- 
stone (fig, ii). Wherever studied, I have found the Logan for- 
mation to consist chiefly of thin sandy beds, rather fine in texture, 
alternating with somewhat argillaceous layers. No stratum suffi- 
ciently thick or coarse in structure to make itself conspicuous 
through differential weathering was observed. Nevertheless, in 
the Mary Ann Furnace section there is one massive layer, a few 
feet above the bed which has been marked Conglomerate II. There 
may be an error in the location of the Conglomerate II, in which 
case the massive layer alluded to belongs to the Black Hand for- 
mation. In this section about 34 feet of the Logan is exposed. 
Above this I have measured approximately 63 feet before coming 
to the horizon where the Pottsville is on the surface; but this inter- 
val of 63 feet is unsatisfactory for a detailed study nor is its con- 
tact with the Pottsville sharp. 
A study of the slopes associated with this formation throughout 
the township warrants the conclusion that the Logan, in vertical 
section, weathers more easily in its upper than in its lower beds. 
No exposure of the uppermost layers of the form*ation was found, 
but from the constant presence of Sharon conglomerate blocks, 
creeping down over the horizon of the Logan, I infer that the 
uppermost layers are the least resistant. 
In the Lost Run section (fig. 2), about 47 feet of the Logan for- 
mation are sufficiently exposed to admit of measurement. 
Pottsville Formation, The state geological map^ gives but one 
area of the Pennsylvanian formations in this township, i. e., in 
the northwest corner comprising about one-third its surface. My 
study of the region shows that at least the Sharon member of the 
^ Geological Survey of Ohio, voL vi, i888. Edward Orton, Sr. So far as Lick- 
ing county is concerned, this map follows the work of M. C. Read in his ‘^Report 
on the Geology of Licking county,” Geological Survey of Ohio, vol. iii, opposite 
p. 529, 1878. 
