MEDINA SANDSTONE. 143 



Again, in Cayuga county, the Medina sandstone appears in the nortli part. At Stirling 

 centre, the exposed rock is about twenty-five feel thick. It appears at Martville, where 

 it is of two kinds : a hard and variegated mass, with diagonal cleavage planes ; and a 

 coarse friable rock, of a color darker than the preceding. 



In Wayne county, at Wolcott furnace, and on Salmon creek about two miles northeast 

 of the furnace, this rock appears in a ravine. It is also quarried on Beard's and Little 

 Red creeks, for building and for hearth-stones. Still farther west, in Monroe county, it 

 appears on the lake shore in the town of Penfield. At the lower falls of the Genesee 

 river, it is exposed for more than one hundred feet. At Medina, on Oakorchard creek, 

 the rock is still better exposed and characterized than at any of the places which I have 

 named. It is better, not because it is thicker, but because there is a better exposure of its 

 fossils than elsewhere. 



From Medina to Lockport, the harder part of this rock crops out near the line'of the 

 canal, or in a terrace which is formed by its protrusion. At the latter place, about one 

 mile below the village, on Eighteen-mile creek, it exhibits the same characters as at the 

 former place. Proceeding from Lockport to Lewiston, it is found forming a part of the 

 slope of the terrace, and contributes principally to its height by the resistance which the 

 hard middle portion has offered to the weather ; while the lower portion, by its rapid 

 change when exposed to the weather, and consequently by its destructibility, gives a more 

 depressed surface to the country under which it lies. At Lewiston, it forms the banks of 

 Niagara river, where it is exposed for two hundred feet. It extends towards the lake, but 

 gradually slopes to its level, and disappears beneath the superincumbent clay. 



Thickness. This rock is thin in Oswego and Lewis counties, but thicker as it extends 

 westward, as we have already observed. It swells to the thickness of two hundred feet 

 upon the banks of the Niagara river. On this river, too, it is more expanded than to the 

 eastward. The entire thickness of the rock, as determined by the survey of Mr. Hall, 

 upon this river, is not less than three hundred and fifty feet. The increase in thickness at 

 Lockport and Niagara, over that of Oswego, is due to additions which were made to the 

 inferior and softer portion of the rock. At Oswego and vicinity the rock is generally 

 hard, and destitute of those softer and argillaceous parts which are so important in the 

 western districts just referred to. 



Agricultural characters of the Medina sandstone. The softer parts of this rock decompose, 

 and form an excellent wheat soil ; but its peculiar properties will be given in another part 

 of this treatise. It is only west of Oswego county, where the rock is adapted by its nature 

 to form a soil suitable to the growth of this grain. 



Surface of the country over which this rock prevails. Two causes conspire to create a level 

 country, through which this rock passes : 1, a freedom from igneous action ; and, 2, even- 

 ness of composition in the rock itself, which secures a uniformity of action so far as at- 

 mospheric agents are concerned. The hard belt of reddish gray sandstone between Medina 

 and Niagara forms an elevated platform, but the country is by no means broken into 



