120 
GEOLOGY OF THE SECOND DISTRICT. 
They are quite even-bedded, with few or no contortions produced by disturbances subsequent 
to consolidation; but the sandy shales are uniformly composed of undulating lamina, pro¬ 
duced probably by unequal accumulations of detrital matter. The entire mass has a slight 
dip to the southwest, though to the eye it appears nearly horizontal. The sandstone layers 
are from four to eight inches thick ; and the materials of which they are composed, are always 
fine, and never a conglomerate or breccia, so far as they are disclosed in the gorges of Lor- 
rain or Pinckney. They become a brown or yellowish brown, by exposure to the weather, 
but are not acted upon very rapidly. The argillaceous shales are disposed to disintegrate ; 
and where they form thick beds, are changed by the weather, both disintegrating and decom¬ 
posing, so that the natural walls are falling and breaking down by the pressure of the super¬ 
incumbent rock. This process is greatly aided by the presence of sulphuret of iron in many 
places ; so that in a thickness of twenty feet, the shale becomes a black powdery mass for a 
depth of several feet, the whole of which has the styptic taste of sulphate of alumine and sul¬ 
phate of iron ; those salts being formed first by the decomposition of the sulphuret of iron, and 
secondly the action of the free.sulphuric acid on the alumine of the rock, and the iron, one 
of the elements of the pyrites. 
The upper parts of the Lorrain shales are highly fqssiliferous, but this condition gradually 
diminishes, so that in the central portion of the rock, only a few fossils are to be found; but 
they are not entirely absent, and what is important to state, is, that some which are abundant 
in the upper part, are sparingly found in the lower also. Thus, the Pterinea carinata is found 
at Lorrain within six feet of the mass or rock denominated Utica slate, where it contains its 
characteristic fossil, the Triarthus beckii. This being the fact, it seems to indicate the pro¬ 
priety of preserving entire the whole mass under one name ; and not, as has been proposed, 
separate the upper from the lower, and make thereby two rocks instead of one. It is cer¬ 
tainly no uncommon thing for a rock to be non-fossiliferous in the lower part, and highly fos- 
siliferous in the upper ; and so far from the fact proving the propriety of making a separation 
in these cases, it rather goes to show that, a separation ought not to be made, especially where 
the lithological characters are uniform throughout the rock. 
Towards the upper part, the Lorrain shales contain a single layer eight inches thick, which 
is close-grained and nearly compact, and also quite extensive, being present in the cliffs in 
Rodman and Pinckney as well as at Lorrain, places which are separated ten or twelve miles 
from each other. It has a very close resemblance to the carbonate of iron of the coal forma¬ 
tion ; and at one place the whole layer has that curious structure denominated cone within 
cone. No fossils are found in this layer, though they are abundant beneath and above it. 
Another stratum worthy of particulat notice, is calcareous, but so meagre and poor, that 
it is no where sufficiently charged with lime as to be worth burning; but it is made up almost 
entirely of fossils, cemented by argillaceous and siliceous- matter. It is rarely more than , 
twelve inches thick; yet it is remarkably persistent, and is found to occupy one position in 
all the gorges of Lorrain, Rodman and Pinckney. It also forms a prominent stratum at Pu¬ 
laski, and at the several localities where this rock is disclosed in the neighborhood of Rome. 
The. Lorrain shales, then, as they exist in Jefferson county, consist of thin, everi-bedded 
