SUPPLEMENTAL REPORT——HOCKING VALLEY 823 
In the Coal Measures of Ohio there are several layers of fossiliferous 
limestone found near seamsof coal, which are very useful in aiding the 
geologist in determining the coal seams. Coal seams were formed of the 
vegetation of broad horizontal marshes, generally near the sea level. If, 
when the land had settled below the water, and the material for a layer 
of limestone had been spread on the surface of the buried marsh, that 
limestone, thus formed, would have a regularity borrowed from the regu- 
larity and evenness of the underlying floor. It is not unusual, however, 
to find such a limestone separated from the coal by several feet of shale. 
Taking for our base the Maxville limestone, as developed in various 
parts of Perry county, we find about eighty feet higher a limestone with 
a thin coal seam under it. In the northern part of Muskingum county, 
I have met with a fossiliferous limestone between these two. From 
twenty to thirty-five feet higher is a limestone, often flinty, under which 
is a thin coal. About forty feet (possibly sometimes a little morc) is 
another limestone, found in the Putnam Hill, opposite Zanesville, which 
is called, in the reports, the Putnam Hill Limestone. There is generally 
a seam of coal under it. This limestone is usually from seventy-five to 
eighty feet below the Nelsonville seam of coal. I have recently found 
it near Straitsville, seventy-two feet below the Great, or Nelsonville, 
seam. Between the Putnam Hill limestone and the great seam, or from 
thirty to forty feet below the latter, we find, sometimes, a thin lime- 
stone with flinty tendency, on which rests the Baird ore found in the 
hills west of Straitsville. This ore appears to have its place at the bot- 
tom of the white sandy clay underlying the coal seam next below the 
Nelsonville seam. Besides these lower limestones, there are two between 
the Nelsonville seam and the horizon of the Pomeroy coal, one called the 
Ames limestone, about one hundred and forty feet below the Pomeroy 
seam, and another, called the Cambridge limestone, about eighty-five 
feet lower. There is another fossiliferous limestone a little below the 
latter, and I have also met with one in more eastern counties, between 
the Pomeroy seam and the Ames limestone. There are, possibly, other 
fossiliferous limestones, but the above-mentioned are the leading ones to 
be found in Perry county, and in the portions of Hocking and Athens 
included in this report. Besides these, there are many other limestones 
which are not fossiliferous, except, perhaps, to a very slight degree. 
One of these has its place perhaps sixty feet above the Nelsonville seam, 
and from it several furnaces obtain their limestone. An earthy buff 
limestone, often nodular and ferruginous, comes in sometimes a few feet 
above the Nelsonville coal. Another limestone is often seen a little 
above the Bayley’s Run coal, and an additional one sixty to seventy feet 
