SOURCE OF 6T. PETEr's RIVER. 3Q7 



Blocks of limestone are found, which appear to be the re- 

 mains of a stratum that has in great measure disappeared ; 

 these are in most cases of a compact and earthy texture, 

 destitute of any organic remains, exhibiting occasional 

 specks of a crystalline nature, which are observed to be 

 calcareous, as, notwithstanding their small volume, they 

 present a distinct rhombohedral cleavage. The first stra- 

 tum which is observed is about eight feet thick, it is form- 

 ed of limestone, presenting a very distinct slaty structure. 

 The texture of the rock is compact, its fracture splintery 

 and uneven ; organic remains abound in it. These are, as 

 far as we saw, exclusively Producti, they lie in the rock 

 as thick as possible ; a small vacant space is generally ob- 

 served between the inner and the outer casts of the shell. 

 This is however generally filled up with a crystallization 

 of calcareous spar; the form of the crystals cannot be made 

 out on account of their extreme tenuity. The colour of 

 this limestone, as well as of the loose blocks found upon 

 it, is a light grayish-yellow. This stratum rests upon ano- 

 ther calcareous bed, which differs from the preceding, in 

 the total absence of organic remains, and in its colour, 

 which is of a light blue. Its structure is more compact, so 

 is its fracture; its horizontal stratification is distinct, but 

 the stratum being thicker, it is more susceptible of being 

 used in building. It produces, in fact, an excellent stone, 

 which admits of being hewn, and which is the chief ma- 

 terial used in the construction of the fort ; this bed is from 

 fifteen to twenty feet thick. When examined with the 

 microscope, the rock presents very general signs of crys- 

 tallization, its texture becomes subsaccaroidal, and veins 

 of calcspar, of an inconsiderable thickness, traverse it in 

 every direction. There are also cavities in which crystals 

 of carbonate of lime, (the cubo'ide ? of Haiiy,) are distinctly 



