Mineralogy and Geology of St. Laiorence Co., N. Y. 221 



some instances it alternates with transition limestone. In some loose 

 rocks of the same kind I have observed fossil tubipora and madre- 

 pora. 



As this transition sandstone does not undergo decomposition, wher- 

 ever it approaches too near the surface of the ground, it is unfavorable 

 to vegetation. Instances of this are rather numerous in some parts of 

 the country. One mile west of the village, this rock forms the surface 

 of near two hundred acres. It is called the Flat Rock of Heuvel. 

 In ancient time there was apparently little or no superficial soil upon 

 it, yet the Lichen geographicus fixed its habitation there. It has in 

 many places been succeeded or accompanied by the Lichen rangi- 

 ferinus, and one or two other varieties of mosses. Never in any 

 other situation have I seen them growing in such luxuriance. They 

 sometimes cover a space of two hundred square yards without the 

 intervention of any other plant, and as they are quite undisturbed, 

 form a verdant carpet from six to nine inches deep on the surface of 

 the rock. The decomposition of the mosses, has produced a small 

 quantity of soil in the crevices ; the pine, fir and oak grow there, 

 but never attain the size of the trees in the neighboring forest. As 

 they cannot strike their roots deep in the ground, they are easily 

 torn up by the wind. 



In many places the rock is quite bare of vegetation ; the contrast 

 between its white surface and the green foliage of the pine, is very 

 remarkable. 



The road between the villages of Heuvel and De Peyster passes 

 over this formation, but such is its extreme hardness, that the wheels 

 of the carriages have not made the slightest impression. If portions 

 of this rock sufficiently large, could be transported to a distance, and 

 deposited in places where rail roads were required, it would com- 

 pletely answer the purpose, with the advantage that the carriages 

 need not be confined to any particular track. 



Ogdensburg, the chief town of the county of St. Lawrence, is built 

 on diluvial soil, covering a formation of siliceous limestone. This 

 limestone may be seen in a quarry, at the western extremity of the 

 bridge over the river Oswegatchie. It is extremely impure. It oc- 

 curs in layers of various thickness, from four inches to twelve. The 

 superior strata, are of a yellow brown color, and contain so much 

 silex and alumine, as to be unfit for making lime. Two miles from 

 Ogdensburg, near the seat of Mr. Copeland, the limestone forms a 

 hill rather elevated. 



Vol. XIX.— No. 2. 29 



