POTSDAM SANDSTONE. 
29 
These layers, from the absence of lime, or this substance not being obvious to the eye, resemble 
portions of the Potsdam ; and having the same composition, and holding the same position, may 
readily be confounded with it, and in fact be referred to either mass, should there be no de¬ 
fined line of separation between the two rocks, none as yet having been noticed in the district. 
About half a mile below Canajoharie, in the cliff by the road side, the rock which is above 
the lower hard solid layers, is in one place much fractured, and in grain and color being a 
light red, could not be distinguished from the sandstone of Potsdam. The surface of some 
of the fragments has anthracite adhering to it, and in forms which show that this substance had 
been in a soft or yielding state. With it, there is also that variety of quartz called mullen 
glass or hyalite, having the same fused appearance as the anthracite, the particles of the two 
substances having been in similar states, and have separated, no doubt, from thermal water. 
In this district no organic remains have been seen in this rock, nor any in the second dis¬ 
trict, excepting the Lingula, at Keeseville, where, according to Dr. Emmons, it is in great 
abundance. The Potsdam sandstone being the most ancient rock of the Transition class, or 
New-York system, its position in the series being perfectly well ascertained, the existence 
of this fossil as the oldest yet known, is a fact of some consequence to those who despise not 
small things, aware that all things are significant. The genus Lingula appears, from this 
New-York fact, to be the oldest known; and, as Mr. Conrad remarks, being also a recent 
one, the genus has lived through all ages of known organic existence. 
That variety which resembles the sandstone of Potsdam, is an excellent building material, 
holding mortar well; and from not condensing moisture so readily as those rocks which are 
more dense, it makes a dry house. It forms a first rate lining for iron furnaces, and is used 
at Lewisburg for that purpose. It is a good guide, at least on the north slope of the Primary 
region, for the discovery of iron ore. There, between the surface of the primary rock and 
the base of the sandstone, the compact red oxide and the specular iron ores have been depo¬ 
sited. The former ore is exceedingly abundant, and is used at Lewisburg furnace, but 
brought from the second district. The same kind of ore is found by the side and base of a 
sandstone ridge, about a mile and a half from the furnace ; but no body has as yet been dis¬ 
covered, though from the abundance of iron froth which exists in the fissures of the rock, and 
amongst the rubbish at the foot of the ridge, it is reasonable to suppose that ore yet exists 
under the sandstone, and was not all swept away by the same causes which have destroyed 
so great an amount of rock in that region, as well as in almost every part of the globe. 
