182 
ERIE DIVISION. 
cropping slopes are often concealed by a thick mantle of its own debris. It forms the 
upper terraces in Schoharie, Carlisle, Cherryvalley, Springfield, Waterville on the road to 
Cassville, Madison and Manlius (where the highest hills are crowned with the Marcellus 
shales), Onondaga and Camillus, shores of Cayuga lake above Springport, at Aurora in 
Seneca county (a little distance south of Waterloo), on Flint creek two miles south of 
Vienna, at the outlet of Conesus lake, two miles south of the village of Caledonia, and on 
Allen’s creek at Leroy. Still farther, and west of Leroy, at Alden, the upper part of the 
rock is exposed ; but generally in this part of the State, the deep beds of drift and debris 
effectually conceal this rock from observation. 
The southeastern exposure of the Marcellus shale, from the northern slope of the Hel- 
derberg to Ulster county, furnishes but few localities of much interest. Upon the hills, or 
rather low mountains west of Leeds or Catskill, Saugerties and Kingston, this rock occupies 
the first distinct terrace, but the debris conceals the strata too much to permit us to observe 
the connections or the fossils. 
Septaria. The Marcellus slate is the first rock which contains those concretionary bodies 
known as septaria. These oval and sometimes round bodies are impure limestones, the 
materials of which were deposited along with the shaly matter ; but in consequence of the 
play of affinities, the calcareous part separated from the great mass of shaly matter, and 
the molecules combined to form the bodies under consideration. During the process of 
drying, the argillo-calcareous matter shrinks and cracks, forming thereby septa which 
radiate from the centre and terminate in the circumference : these are subsequently filled 
by infiltration, either of calcite or the sulphate of barytes or strontian. In the formation 
of septaria, we are furnished with a beautiful as well as a striking illustration of a series 
of molecular changes, which the strata may and do undergo during the process of soli¬ 
dification ; and indeed we may be well assured that even the solid strata are continually 
undergoing extensive changes, in consequence of the ever active and energetic forces with 
which matter is endowed. Hence it is important, in speculating upon the conditions 
of strata, to bear in mind the fact that matter is never quiescent; never reaches that dead 
point where it is destined to remain stationary. Freedom of motion is found in fluids : in 
the tenacious clays, the particles are freer than in the granite of the mountains ; but even 
here they feel the force of molecular attraction, which results in regularity though not in 
stability of form ; for heat and cold must continually modify the shape of the particles, by 
altering the saliency of their angles. 
Limestone stratum associated with the Marcellus slate. At Schoharie, Cherryvalley and 
Manlius, a black limestone, from five to ten feet in thickness, occupies a position in the 
midst of the shales. It is an argillo-calcareous rock, and probably is capable of forming an 
excellent hydraulic mortar. It weathers out into extremely rough masses, so that persons 
who have occasion to work the rock generally call it chawed rock. In the Helderberg, this 
mass is concealed by debris, if it exists there ; and it is not distinctly recognized in the 
western counties. The composition of this limestone does not differ materially from that 
