-No. 275.] 273 
The upper layers of the group are from 3 to 4 feet thick, sometimes 
subdivided into what are called courses. There are but two layers of 
water lime separated by bluish black limestone, which is generally dis- 
posed to separate into courses, whilst the layer of limestone which is 
above the upper water lime is broken up by lines of fracture, in all 
directions. This is the layer which is most commonly burnt for Hrne, 
In general, the upper layer of water lime requires less heat from being 
of a less dense nature than the lower layer. 
From the eastern end of Madison county, extending east through the 
Third District, there is a series of limestone layers which are not found 
beyond that boundary to the west^ These layers are characterized by 
the Pentamerus knightii, Euomphalus profundus, Delthyris pachyoptera^ 
D. macrapleura, Apiocrinites, &c. &c. and have not been seen west of 
the falls of Oneida creek. 
These layers are followed to the east by a series of argillaceous lay- 
ers full of that singular marine plant, the fucoides canda galli. 
The omission or absence of these two series to the west, causes the 
next series of layers to repose immediately upon the water lime group. 
This is the white sandstone noticed on the hill at the falls of Oriskany, 
and for the present may be called the Oriskany sandstone. This sand- 
stone is well known to extend over many of the States, occupying, 
like all geological masses, a fixed position in the whole series, but is 
exceedingly variable as to thickness. According to the report of the 
State geologist of Pennsylvania, it is there 700 feet thick. At Oris- 
kany falls, about 20 feet on the road from Elbridge to Skaneateles, it 
is over 30 feet. At the quarries near Auburn, it is from a few inches 
to about 2h feet; and at Split-Rock, near Syracuse, it shows itself in 
some parts by a mere sprinkling of sand, observable on the bottom of 
the layer which covers it, and in other parts by a thickness of about six 
inches. 
This sandstone is the rock of which the lock at Jordan, not Lyons, 
was constructed. It was quarried on the road from Skaneateles, which 
goes by the east side of the outlet towards Weedsport, The lower 
part of the sandstone abounds in fossil shells remarkable for their great 
size. Most of them, if not all, are found in the gray sparry crinoidal 
limestone, which rests immediately upon the sandstone, and so far as 1 
have had time to attend to their examinations, seem to be confined to 
the two rocks. 
I Amm. No. 275.| 35 
