360 
GEOLOGY OF THE SECOND DISTRICT. 
Observation had long since proved that a given mineral substance, occurring in veins, -was 
liable to be unproductive when it deviated from its usual course. It is a matter of some 
importance to be able to find, in this country, not only the same general arrangements and 
associations as in Europe, but the same leading facts in the distribution of mineral matter. 
LOWER MEMBERS OF THE NEW-YORK SYSTEM. 
I have divided the surface rocks of this county into three classes : the primary, which oc¬ 
cupies the whole of the eastern and southeastern parts; the sandstone, which is nearly 
central; and the limestone, which occupies a belt along the St. Lawrence river. A very large 
proportion of the district occupied by the first class of rocks is still covered with forest, and 
is only generally known, or it has been particularly examined in only a few places. The other 
districts are well known, and they are as different in character from the first as possible. The 
only mineral productions are derived from the first by transports, as the bog iron ores, or else 
are confined to the rocks themselves. 
Potsdam Sandstone. 
The quarries of this rock at Potsdam are situated upon the De Grasse river, three or four 
miles southeast of the village. They are sixty or seventy feet thick. The rock at this place 
is composed of moderately fine particles, and very uniform in size ; hence it is even-bedded ; 
and what is worthy of remark, is the perfectly smooth and even surfaces which the layers pre¬ 
sent. Thin sheets of the rock, twenty-five or thirty feet square, can be raised without diffi¬ 
culty. The layers vary in thickness from one inch and even less, to two feet; but each wide 
layer, though no distinct seam appears, may be separated into many, so perfectly fissile is the 
rock. The general color of the mass is yellowish brown, but the tint of each layer differs 
somewhat from those adjacent to it; so that the rock, upon the fractured edges, wears a slight¬ 
ly striped aspect. 
This quarry furnishes the most valuable stone in the State, being so perfectly workable and 
manageable, especially when first raised, that few materials for building could compete with it, 
if situated near a market. As it is, the Potsdam sandstone is largely employed for building 
in the adjacent towns. It has been transported sixteen miles overland for this purpose. The 
buildings constructed of this material present a remarkably neat appearance ; and as the rock 
is free from sulphuret of iron, it does not appear stained and soiled after a few years exposure 
to the weather. 
In addition to the common purposes of building, this rock is largely employed as a fire¬ 
stone ; hence it is used for the hearths of furnaces, for which purpose it is peculiarly well 
adapted, by reason of its granular structure, and the entire absence of crystalline action. 
The phenomena presented by this rock are rarely of an interesting kind. The stratification 
is usually quite perfect, though we frequently saw instances of diverse stratification, as in the 
following diagram: 
