120 CHAMPLAIN DIVISION. 



may all be seen in juxtaposition in the order in which I have named them : in fact, at 

 many places in the immediate neighborhood of St. Albans bay, the brown may be found 

 passing into a whitish calcareous rock ; but it is no where so distinct as at and near Bur- 

 lington and Addison (Vermont) . 



All the preceding varieties occupy the lowest part of the rock ; although, at the locali- 

 ties I have given, one or two of them constitute the whole of the mass. 



Then again the Calciferous sandstone, when examined in its superior connections, is 

 found quite as protean as in those masses which connect it with the Potsdam, or the Pri- 

 mary system, when the former is absent. For example, at Chazy, it furnishes a mass 

 from 150 to 200 feet thick, composed of encrinal remains in fragments. I include, how- 

 ever, the fine oolite, and some subordinate beds which arc highly charged with remarkable 

 fossils. Some of these beds are sufficiently calcareous to form good quicklime, and even 

 some of them are quite pure marbles of a reddish color. Subordinate to the whole rock, 

 we may discover, at many points, beds of chert, and beds of large concretions or extremely 

 coarse oolite, together with those masses which are commonly called waterlimes or hy- 

 draulic limes, and which may be known by their drab colors when weathered. This last 

 mass might with propriety be reckoned as one of the principal varieties of the Calciferous 

 sandstone. 



The preceding may be recapitulated in the ascending order thus : 



1. Blue compact limestone, and often sparry, but the planes of deposition obliterated. 



2. Brown or chocolate sandstone, passing into both a fine white limestone and the ordinary gray 



sparkling limestone. Both varieties are confined to the east side of Lake Champlain. 



3. The ordinary gray calciferous sandstone in thick beds. At the base of this variety, in the Mohawk 



and Champlain vallies, the drab colored or hydraulic limestone mostly occurs. 



4. Superiorly are the important beds of encrinal limestone. Traces only of these beds occur in the 



Mohawk valley. Chazy is the only locality in New- York, where they exist in force. 



Mineral contents. The minerals peculiar to this rock, belong mostly to the third variety ; 

 and they all occur in irregular-shaped cavities, some of which are the size of a four-quart 

 measure. 



1. Limpid quartz, containing water and anthracite. At Middleville, Littlefalls, also thick beds of chert 



or flint. 



2. Sulphuret of iron. Many places in the Mohawk valley, 



3. Sulphate of barytes. Franklin county. 



4. Calcareous spar, associated with the limpid quartz. 



5. Sulphate of strontian, less common than the barytes. 



Diversity in the composition of this rock. I have already noticed the most remarkable 

 kinds of Calciferous sandstone. In the Mohawk valley, and also surroimding the great 

 primary nucleus north of the valley, this rock is uniform in its composition, and easily re- 

 cognized by its lithological character ; but those masses adjacent to the Champlain valley 



