Ko. 275.J 281 ^ 
It is said that when the waters first flowed off by the opening of the 
ditch J it carried with them the muck which covered the marl, leaving 
a snow white surface of marl, co-extensive with the whole area which 
was drained. Imperfect attempts have been made with poles to ascer- 
tain the thickness of the marl, but without effect, no bottom could be 
reached. The ponds or marshes west of the swamp, called the Green 
ponds, have also bottoms of marl; so likewise has the Vlie or natural 
meadow to the south of the swamp. 
The great swamp of Onondaga is the prolongation of the Cowassa- 
Ion, and like it, is of marl also. Innumerable are the minor localities 
met with in going along the Erie canal towards the west boundary of 
the District. 
Lake marl is likewise found in many places upon the great elevation, 
In the lake-like depression north of Peterboro', after crossing over a 
low stony ridge on the road to Perryville, the road traverses a level 
swampy bottom, the ditches for drainage being dug in lake marl. The 
lakes to the southwest of Tully corners are all marl lakes; so likewise 
are the ponds above Hamilton village, which serve as feeders to the 
Chenango canal, and likewise other small ponds in the south part of 
Onondaga and Madison counties. 
Tufaceous Iron. 
On the land of Robert Riddle, one mile west from Chittenango, I 
was informed that there was a deposit of iron^ portions of which had 
been carried over Oneida lake, but the owner of the ore received no 
encouragement from the owner of the furnace. I found it to be -a cal- 
careous tufa, stained with hydrate of iron, and noticed that the spring 
whose water deposited the tufa, gave no signs of iron, but that the ore 
came from the sluggish water of the boggy soil above the tufa. In 
some of the masses of ferruginous tufa there was a coating of oxide of 
manganese. 
The same kind of tufa, stained with oxide of iron, is found on the 
land of William Wheeler, about two and a half miles northeast of Sa- 
lina. For a few hundred yards on a slope to a swamp north, there is 
a deposit of tufa, the upper part of which is in some places deeply 
stained with oxide of iron. As the deposition of the tufa is constant- 
ly going on, the soil, which is composed of muck chiefly, rises. It is 
from the soil that the iron is derived, as mentioned in the first report of 
the Fourth District. That the iron is furnished from the soil, is evi- 
dent from the fact, that the lower part of the tufa is not stained with 
[Assem. No. 275.] 36 
