132 
GEOLOGY OF THE FOURTH DISTRICT. 
1. Irregular mass, much broken up by the denuding agency . 3 feet. 
2. Light drab or ash-colored limestone with irregular cavities . 4 “ 
3. Thick bed like No. 2, with cavities containing celestine, etc., slightly striped below .... 4| “ 
4. Consists of two strata, which are ash-colored and striped with darker; brittle after expo¬ 
sure ; siliceous...... 5 “ 
5. Thin-bedded, bluish, and striped with lighter colored; bed of quarry. 4 “ 
About three miles farther west, at Caledonia village, the terminal strata are thin-bedded and 
of a light drab color, and more argillaceous than in many other localities. The rock also 
appears on the farm of Donald McKenzie, one mile north of Caledonia village, and at nume¬ 
rous places along the brow of the terrace west of Mumford’s mills. In some places the rock 
is porous, or contains irregular cavities; in other places, it is compact and regularly bedded. 
At Leroy falls, the whole thickness of this rock is exhibited, together with its connexion 
with those below and above. The upper part is thin-bedded, in regular strata; the middle 
consists of several thick strata ; the whole of a light drab color. 
At Morganville in Genesee county, nearly the same order of the strata occurs; the thick 
beds are more siliceous than at Leroy falls, and they contain some irregular cavities. The 
connexion of this group with the higher masses is well exhibited in the bed of the stream at 
this place, while the fall is over the thick-bedded portions of the deposit under consideration. 
By making examinations along the northern slope of the terrace which extends westward 
from the Genesee, this rock may be seen in nearly every ravine or gorge which indents the 
regular outline. It appears beneath the cherty layers of the corniferous limestone, two miles 
north of Batavia. The thick-bedded portions form the falls of the Tonawanda on the Indian 
reservation. At Falkirk in Erie county, this mass, capped by the corniferous layers, has 
formed a fall and rapids of seventy or eighty feet. It again appears at Clarence Hollow, in 
a few thin-bedded strata, with cavities lined with spar; and again at Williamsville, in thin 
regular strata, which are burned for hydraulic cement. 
Three miles east of Buffalo, the same strata appear in the bed and banks of Conjockety 
creek. The upper beds contain cavities filled with rhombic spar and sulphate of strontian. 
Many of the smaller cavities which abound in the higher layer, are produced by the destruction 
of a species of Turbinolopsis, casts of which sometimes remain studded with minute crystals. 
At Black-Rock the higher strata of this deposit appear, having the same character as just 
described. The Turbinolopsis was abundant at this place, and its casts remain partially 
filling the small cavities. 
This rock is the product of a period intervening between the deposition of the great 
mass of the salt group, which is mostly a mud deposit, and the commencement of the 
limestone formations above. The character, therefore, partakes of the nature of both, being 
an argillaceous limestone, with a small admixture of siliceous matter which probably resulted 
from an intermingling of the materials which gave rise to the Oriskany sandstone, or a thin 
deposit which seems to be its representative, and every where follows this rock in the Fourth 
District. The ocean, which had been rendered turbid by the immense deposit of mud forming 
