38 GEOLOGY OF THE THIRD DISTRICT. 



dal layers, Uioiigh they form one group from the intercalation of tlie latter, they will be treated 

 of separately, from the rule which separates objects that are different. 



Calciferous Sandrock. The greatest exposition of this rock is at the four greatest uplifts, 

 such as the Noses, particularly at the east end ; at Little-Falls, Middlevillc and St. Johns- 

 ville ; very little of the fucoidal layers being seen at those places. At these, and at other 

 localities, the characters of the rock arc similar : generally fine grained ; somewhat sparkling 

 when fresh fractured ; of a yellowish grey, which becomes darker when long exposed. Be- 

 sides these general characters, it exhibits numerous others not necessary to detail. Its layers 

 are irregular in their outline, contrasting strongly with the fucoidal layers, and especially 

 with the birdseye limestone in that respect. They are usually much fractured when long 

 exposed in a cliff. It forms a thick mass at all the places mentioned, being upwards of two 

 hundred feet thick at the Noses and Little-Falls. There are many other points where it also 

 appears as a cliff, showing a considerable mass, such as the continuation of Flint hill at the 

 east end of the district on the Mohawk river, the quarry opposite St. Johnsville, and some 

 other places, as must be obvious from the amount of surface which the rock shows in Mont- 

 gomery county ; but these do not require a more particular notice. 



From the composition of this rock, consisting of carbonate of lime and silex, it was highly 

 favorable for the forming of other products, when placed under circumstances admitting of 

 solution, this being the first step towards production. 



At Little-Falls, in many parts of its mass there are thick layers, showing a concretionary 

 structure, as in the agate ; but when in great mass, the material is coarse, usually presenting 

 a series of dome-shaped bodies, placed side by side, of an inch or more in diameter, and more 

 or less regular : occasionally they appear globular. The former kinds are composed of the 

 rock ; the latter is of silex or flint entirely, which is common also, but not in great masses. 

 Some of this latter kind presents the more common forms of agate. 



At tlie Noses, siliceous concretions are more abundant, and in greater variety. One of the 

 best points for observing them is on the south side of the river, and at the east end going by 

 the road which leads by the side of the uplift. Among the various forms are the oolitic ; the 

 oolite particles opaque, their cement glassy quartz. Others show that minute or very thin 

 layers had formed, and were subsequently broken up, the edges in parts slightly rounded and 

 diminished in thickness, as though solution had commenced before the whole were demented 

 or made solid. Tlie oolite was found in many other localities, such as Spruce creek, a few 

 miles above the paper-mill ; Fish-House, &c. The surface of the rock, at the falls in East 

 Canada creek in Manheim, shows numerous places where thin layers had been formed and 

 broken up, and the parts disposed with a regularity not unlike particles of iron when placed 

 upon glass and subjected to the influence of magnetism, or particles of another kind when 

 acted upon by electricity. 



Among the other siUceous productions to which the solution of the rock has given rise, are 

 quartz crystals. These are in some places in great number, and numerous perfect ones have 

 been found as to form and transparency. Their interest is greatly increased by association 



