No. 200. 1 
215 
This rock is a true sandstone, of a red, yellowish red, gray, and gray- 
ish white colours. It is made up of grains of sand, and held together 
without a cement. Intermixed with the silicious grains are finer parti- 
cles of yellowish feldspar, which do not essentially change the character 
of the sandstone, but they show the probable source from which the ma- 
terials forming it were originally derived, viz. some of the varieties of 
granite. Unlike, however, most of the sandstones, it is destitute o * 
scales of mica. The colouring matter of the rock is evidently oxide of 
iron, but unequally diffused through it, giving it intensity or deepness 
of colour in proportion to its quantity. In some places it is almost 
wanting, which makes it, when pulverized, a good material for glass. — 
The grains and particles in its composition are general angular, but where 
it takes the character of a conglomerate, as it does in the inferior layers, 
they are frequently rounded. The thicker strata exhibit an obscurely 
striped appearance, owing to prevalence of certain colours in the different 
layers. 
Two properties possessed by this sandstone, increase, essentially, its 
value for all the purposes to which it can be applied, its durability, which 
is owing to its silicious character, its evenness of grain and strata, which 
facilitates and lessens the labor of quarrying, and afterwards saves the 
expense of dressing, preparatory to its employment as a building mate- 
rial. Both of these characters fits it admirably for every kind of use to 
which stone is ever required. As a fire stone, nothing can be found bet- 
ter, and if it is required for durable public works, as the locks of canals, 
&c., no material can be found better suited for the purpose. 
The strata on the Racket river, where the principal quarries are open- 
ed, rise about 65 or 70 feet above the water. The quarries extend some 
10 miles along this river, which has apparently cut through the rock, and 
exposed the strata on each side, dipping to the northwest, at an angle of 
about 30°. I have not ascertained the whole thickness of the beds. — 
The layers vary in thickness from i an inch to 4 feet, so that every va- 
riety may be obtained; and the thicker strata may be split to any requi- 
site thinness for which they may be w^anted. Slabs, having any super- 
ficial area, which can be used, and of the given thickness, may be quar- 
ried with ease. The waters from which this sedimentary rock were 
formed, must have been in a perfectly tranquil state, to have preserved 
such a regularity and evenness of surface, and freedom from contortion. 
Such a state did not prevail every where, even in the immediate vicinity 
of Potsdam, for at De Kalb, in the same formation, there are some very 
remarkable contortions and disturbances. 
