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 boars 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 Ijreak 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 efiect 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 cjuarried at Lockport. 3. A still harder sandstone, possessing 

 somewhat the cliaracters 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 nunal or elevated escarpments, but in deep ravines which have been cut in the 

 rock by rimning 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 xipon 

 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. Tlie upper layers at this locality are 

 light colored, somewhat variegated as usual, and covered \n\\\\ 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. 



