REVIEW OF GEOLOGICAL STRUCTURE. 25 
acters and fossils are identical with those of the Maxville and Logan - 
limestones, such as have apparently resulted from the destruction of 
these limestones by the forces which, at a later date, spread the Con- 
glomerate. Hence, we must conclude that the Conglomerate of Northern 
Ohio is more recent than that of the Hocking Valley, and that Coal No. 
1 of Mahoning. county is not, as formerly supposed, identical with the 
Jackson shaft coal. | 
In the Sub-Carboniferous coals of Southern Ohio, we have additional 
evidence that the submergence which resulted in the formation of the 
Lower Carboniferous limestone was progressive from the south toward 
the north. They show that the Waverly shore of the Carboniferous sea 
was for a time marshy, and sustained a luxuriant vegetation that pro- 
duced the accumulation of peat, and that, by subsequent subsidence, the 
sea water flowed in over this shore, covering the peat beds with thin 
sheets of organic sediment derived from the hard parts of the mollusks 
which inhabited the Carboniferous ocean. At a later date continued 
sinking of the surface resulted in the formation of other peat beds, lime- 
stones, etc., but the water which buried or deposited these was not that 
which formed the Maxvilie limestone, but came from a different source, 
and was, perhaps, fresb. . 
THE CONGLOMERATE. 
In the description of the development of the Conglomerate in Ohio 
contained in the first and second volumes of this report, nearly all we 
have learned about it is told. It seems necessary, however, to refer to 
one or two errors which have become current in regard to this rock, and 
which require correction. 
First. It is believed by some that the Conglomerate nowhere extends 
under the Coal Measures, but forms a bank or rim around the margin of 
the basin. 
Abundant evidence of the falsity of this theory is, however, fur- 
nished in the reports and maps descriptive of the geology of Mahoning, 
Trumbull, Portage, Summit, Medina, Wayne, Holmes, and Licking 
counties, contained in this or the preceding volumes of our report. In 
all these the Conglomerate is shown to pass under Coal No. 1. It is true 
that the greatest development of the Conglomerate is north of the coal 
field, and that it is rarely struck in borings made towards the central’ 
portion of the basin. It is reported, however, in a number of localities, 
and has been missed in many others, simply because it was not reached. 
There are sometimes forty or fifty feet of light shales interposed between 
the Conglomerate and Coal No. 1, and as these have been considered 
‘‘ bottom rock,” the berings have not been carried deeper. The Conglom- 
