POTSDAM SANDSTONE. 29 



These layers, from the absence of hmc, or this substance not being obvious to the eye, resemble 

 portions of the Potsdam ; and hacfit^ 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 forrhs 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. 



