STRATIGRAPHICAL ORDER. oil 
and Middle Kittanning. The 20 feet of white clay would then be the 
Kittanning clay, but the limestone, No. 18, is the surest element of the 
section, and this makes the first interpretation the more probable one. 
By comparing it with the Kimbolton section, Fig. XVI, it will be 
found to agree very closely. 
The Cambridge coal field is thus seen to be the third important de- 
velopment of the Upper Freeport seam in Ohio, the Salineville, and the 
Connotton Valley fields having been already referred to this horizon. 
Coat SEAMS OF;THE,LOWER TuscCARAWAS AND MuskINGUM V ALLEYS. 
Returning}from this detour to the work of tracing the westward 
extension of the general section thus far followed, we can assure our- 
selves, as has been already said, of theSintegrity and unbroken conti- 
nuity of our series in this direction, by the measurement of a few well- 
selected intervals. Even these are not essential to the establishment 
of such continuity,3forjno question has been raised as to this fact. Every 
geologist that has worked in the field has been obliged to accept and 
adopt the universal belief of land-owners and coal miners throughout 
the territory, that the Pike Run coal, the New Comerstown coal, the 
Coshocton coal, the Rock Run coal, the Upper Dresden coal, the Up- 
per Zanesville coal, are all one and the same seam. It is the No. 6 of 
Newberry in the Tuscarawas Valley, and the Middle Kittanning coal 
of the Pennsylvania series. In fact the mines and country coal banks 
opened in this seam, throughout this territory, effect as close an approxi- 
mation to visible continuity as we can find in any like part of the 
Lower Coal Measures. 
A few sections will here be introduced, covering and fairly repre- 
senting this wonderfully steady portionjof the margin of our coal field. 
The section at Zoar Station and Mineral Point has been already 
-described in part, but it will be repeated here in connection with the 
others that are selected. In Figs. XIX and XX the following sections 
are represented : 
XIX. <A. Zoar Station and Mineral Point. 
B. Lot 30, Dover township, Wm. Swaby’s farm. 
: C. York township, Franz Ankeney’s farm. 
XX, Glasgow-Port Washington Furnace tract. 
New Comerstown and Bird’s Run. 
Beech Hollow, 2 miles east of Coshocton. 
Ano 
