142 
ONTARIO DIVISION. 
§ 1. Medina sandstone. 
This rock, as its name indicates, is a sandstone, taken as a whole ; but when examined 
in some places, it bears but a slight resemblance to a rock of this kind, though at these 
locations it has undergone an important change from atmospheric influences. Thus, on 
the Niagara river, it is a soft marly rock, cracked and broken, or ready to break into short 
columnar masses, which in their turn are still farther changed, and which finally pass 
into an argillaceous paste, or an argillaceous soil when dry. That this is the effect of 
weathering, appears from the fact, that where the deeper parts are exposed, it is a sand¬ 
stone, which retains its original characters for a time, but finally disintegrates, and becomes 
in process of time a soil, as has been stated. 
The Medina sandstone is a red rock, or else is red and mottled with green. It is never 
a white sandstone for any considerable distance, but retains a tinge of red. Some parts 
are harder than others ; and, when viewed in this light, it may be divided into the follow¬ 
ing kinds : 1. The inferior mass, which is a soft and mottled sandstone, which may, by 
exposure to the weather, become still softer. 2. A hard sandstone, suitable for flagging, 
and, as such, is extensively quarried at Lockport. 3. A still harder sandstone, possessing 
somewhat the characters of a conglomerate : it is lighter colored than either of the pre¬ 
ceding. The soft inferior sandstone is repeated, and lies upon the thin-bedded flagging 
stone of Lockport. 
Extent and distribution. This rock, which is colored brown upon the Geological Map, 
extends from Oswego to Niagara river, in a narrow belt upon its south shore. It has been 
extensively denuded, but is notwithstanding a well defined rock. It rises but a few feet 
upon an average above the surface, through this entire route ; and hence, where exposed, 
it is not in mural or elevated escarpments, but in deep ravines which have been cut in the 
rock by running water. The harder parts have resisted this force for a time, and perhaps 
have formed falls and cascades. The deep gorges of the Genesee and Niagara rivers are 
the most important and interesting places for examination. But it is advisable that the 
localities where this rock appears, and where it may be examined, should be more dis¬ 
tinctly described. 
The rock, then, appears first in the northeastern part of Redfield, in Oswego county. It 
there forms a thin stratum in the most elevated part of the town, reposing directly upon 
the grey sandstone already described. It appears again in Oswego, on Little river, near 
Panther lake, extending about one-fourth of a mile. It occurs again near Amboy centre, 
and also in Colosse at Petrick’s mill : this locality furnishes a hard variety, and free from 
argillaceous matter. Then again it forms the lower fall at Mexicoville : this is the lowest 
part of the rock. The best and largest exposure of the rock in Oswego, is at Fulton, 
where it appears on both sides of the Oswego river. The upper laj^ers at this locality are 
light colored, somewhat variegated as usual, and covered with the peculiar fossil of this 
rock, the Fucoides harlani. Some layers of slate appear a few feet below, which are suc¬ 
ceeded by red and gray sandstone, suitable for building materials, hearth-stones, etc. 
