34 
GEOLOGY OF THE FOURTH DISTRICT 
9. MEDINA SANDSTONE. 
Saliferous rock, of Eaton ; Niagara sandstone, Red sandstone of Oswego, Variegated 
sandstone, and Red marl and sandstone, of the Annual Reports. 
(No. 5, of Pennsylvania Survey.) 
This mass is usually a red or slightly variegated sandstone, solid and coherent in the eastern 
extremity of the district, becoming friable and marly in its western extension, and admitting 
an intercalated mass of grey quartzose sandstone which contains marine shells ; while in the red 
portions, are rarely found other than marine-vegetables or fucoids. This rock gives origin to 
brine springs throughout its whole range. It extends westward beyond the limits of the 
district into Canada, but is not known in the southwest, in Ohio and Indiana. Both in Penn¬ 
sylvania and Virginia, it is found possessing the same essential characters as in New-York. 
The locality which gives the name, exhibits the rock best developed, and with its charac¬ 
teristic fossils. The rock is the lowest of the district, and the ninth of the New-York System 
in the ascending order. 
By reference to the Geological map of the State, it will be seen that this rock extends 
throughout the district from east to west, bordering Lake Ontario. It forms but a narrow 
band in Wayne county, but expands to the westward, and seems to attain its greatest thick¬ 
ness near the Niagara river; as is indicated by the breadth of surface occupied by the mass, 
