256 Remarks on American Rock Formations. 
of such rocks, (old rocks with mechanical products,) and the 
nearer they are to the level of the ocean, the more likely they 
are to be horizontal. This rule is the result of observation, 
and of a theory, which I may, hereafter, give to the world. 
In the states of Ohio, Kentucky and Tennessee, the oldest 
rocks, or those lowest in position, I found to be characterized 
by the same shells and fossils found at Trenton Falls in 
York, which are similar to the shells and fossils, which char- 
acterize the transition rocks of Europe, namely, the orthocera- 
tite, trilobite, productus spirifer, and others of the new genera 
of Sowerby. ese may be added the many species of 
favosi, and the isotelus of De Kay, which | found in this, 
at Frankfort in Kentucky, and at Nashville in Tennessee. 
All these products I observed were below the bituminous 
shale ; for where it commenced these products disappeared, 
the encrinie taking their place along with terebratula. 
Above the coal shale were terebratula, and that species 
of Linnewan madrepora now the genus stylena, Those 
formed the characteristic of the most modern rocks I met 
with. It is worthy of remark, that all the barrens I crossed 
over, consisted of the rocks above the shale; and the finest 
lands of the three states I visited, had their soil underlaid’ 
with the rocks below the shale. In these latter, little or no 
siliceous particles are observable, whilst, in the rocks above 
the shale, they abound ; they form nodules, irregular masses, 
&c. All the stylena, which are very numerous, are replaced 
with silex. It is to these siliceous masses, that the barren 
nature of the country is owing; for drought being frequent, 
and they being good conductors of heat and bad absorbers 
and retainers of moisture, vegetation does not find the con- 
itions for vigorous life, as is found where they are absent. 
Most of the French geologists I studied with, assigned to 
the transition the bituminous coal deposition, making it the 
last member of that class; so with those, who are governed 
by authority, I presume, this will have weight. With myself 
it is sufficient to know, that the shells and fossils mentioned, 
are of the same genera with the transition rocks of Europe— 
our types; that, as in our country, they abound in such 
rocks, and if found in more modern rocks, they occur but 
occasionally ; that such rocks in the western country cqntain 
no coal; ali the coal there, is in rocks posterior to them. 
