4AG GEOLOGY OF OHIO. 
rock (t. e., hard rock) appearing, except near the lock.” At McConnels- 
ville the dam is built upon a “soft, shelly rock.” At Rokeby “no rock 
was found, and the dam is built upon a sand foundation. At Taylors- 
ville the dam is built upon the bed-rock of. the river. At Zanesville the 
dam is upon the bed-rock. At Symmes Creek the dam and lock are on 
soap-stone at the east end, but no rock was found at the west end within 
a depth of sixty feet.” 
The Muskingum and Licking rivers, at their junction at Zanesville, 
flow upon the hard, stratified rocks, the most important of which is a fos- 
siliferous limestone. Under Putnam Hill we see the rock strata extend- 
ing beneath the water. About a half a mile below, on the east side of 
the Muskingum, we find the stratified rocks also extending out under 
the river. It is, however, quite possible that the Licking once had a 
deeper channel east of the present one, and united with the Muskingum 
much higher up the latter stream, and from that point the united 
streams flowed under the present site of the city, coming into the exist- 
ing channel down toward the lower lock on the canal. If this were so, 
the Drift gravel choked up this old channel, and both streams flow now 
upon the marginal rock platform which was once the western shore. 
The falls of the Hocking, at Logan, are in a hard conglomerate—the 
top of the Waverly conglomerate—while east of the falls the alluvial 
sands extend down lower than the surface of the rock at the falls. At 
these falls there are many pot-holes. In a mining shaft sixty feet deep, a 
mile or two above Salina, in the immediate valley of the Hocking, the 
usually heavy sandrock over the coal was found to be eroded, leaving 
only a very few feet of it, and in a drift-way from the bottom of the 
shaft a pot-hole extending through the sandrock into the coal seam was 
struck. In the explorations considerable quantities of buried ¥ood were 
found. The erosion of the rock and the pot-hole would indicate that in 
the pre-glacial time there had been at this point falls or rapids. The 
 ghaft revealed nothing but alluvium in penetrating to the sandrock, no | 
true Drift materials being found. In a well near this shaft the lower 
jaw of a mammoth was found sixteen feet below the surface. Before the 
Drift, we may reasonably believe that the larger streams of south-eastern 
Ohio showed exactly the same inequality in their beds that would natu- 
rally be made by streams of considerable current passing over strata of 
unequal hardness, and exactly such as has been made by the Kanawha 
and other streams in similar geological formations south of the Ohio, in 
West Virginia, and beyond the region of the Drift. There were ledges 
of hard strata crossing the channels and making falls and rapids, while 
below were pools of varying depth, partially filled with sand and mud. 
