122 
GEOLOGY OF THE SECOND DISTRICT. 
doubtedly chemical, and consisted in the separation of the siliceous and calcareous parti¬ 
cles from the general mass, and of their segregation into central points of attraction. If, 
under these circumstances, an impulsive or mechanical movement was given to it, those 
centres of attraction, composed of siliceous or calcareous matter, could not but be obliged 
to move on each other; and the softer coating which surrounded, or in which they were 
enveloped, would necessarily be pressed and compacted about the harder, which would pro¬ 
bably result in the formation of polished, but flattened masses. 
3. Of calcareous shales. —They eflervesce briskly with acids; they consist, therefore, of calcareous and argillaceous 
matter intimately mingled, and probably in about equal proportions, though they are more shaly than calcareous to 
the eye. They are fine-grained, and destitute of lustre, but sometimes contain glistening scales of mica. Seams of 
quartz and calcareous spar traverse the beds in many directions. Geodes, containing crystals of quartz and lime, 
are common ; or what is more frequent, the spar is in crystals, either in acute rhomboids or dodecahedral prisms. 
The color of this mass is bluish grey, with a texture very uniform. It is massive, and 
does not split into flag-stone, and the pieces of the rock are quite angular. It is a durable 
stone, and only slightly affected by the weather. Most of the shales and sandstones at 
Lorrain become yellowish brown by exposure; and in this particular, there is a sensible 
difference. 
In this mass, I never have been able to discover fossils, except some obscure markings 
similar to fucoids. The materials composing it appear to have accumulated rapidly, which 
might have interfered with the due performance of the functions of life. The thickness of 
this mass is about sixty feet. 
4. 0/ thin beds of limestone, always fine-grained and earthy, and variously checked with seams of calcareous 
spar. 
These beds may be considered as way-boards, or layers which mark the direction of the 
planes of deposition. They are mostly impure, but sometimes may be employed for lime. 
They are, however, rarely more than one foot thick ; and hence, under ordinary circumstances, 
the labor and expense of quarrying are too great to be profitable. 
5. Of beds of flinitj slate, with sharp cutting edges and conchoidal fracture ; color green and bluish black ; per¬ 
fectly close-grained, or compact like flint or jasper. 
The beds of flinty slate are often checked with seams of white or grey quartz, and some¬ 
times with calcareous spar, and the surfaces covered with implanted crystals of lime, quartz 
and sulphuret of iron. 
6. Of calcareous breccia. —The mass is made up of angular fragments of limestone and a slaty sandstone, be¬ 
tween %vhich there intervene seams of calcareous spar. 
It is sometimes in beds from thirty to fifty feet thick ; and so compacted together, and com¬ 
posed of so much calcareous matter, that it may be employed for marble, as at Swanton, 
Vermont; but as it occurs along the Hudson river, it is unfit for this purpose, in consequence 
of containing so much slate and dull earthy matter, and an imperfect incorporation of the 
materials. 
