376 PALEOZOIC TIME. 



2. Ohio Section. 



Lower Silurian. 



Primordial, Potsdam Epoch. — Whitish calcareous sandstone, 316 feet or more — (at 



bottom of the " State House well "). 

 Canadian, Calciferous Epoch. — Drab, sandy, magnesian limestone, 475 feet — (passed 



through in boring the " State House well "). 

 Trenton, Trenton, Utica, and Cincinnati Epochs. — Limestones and calcareous shales 



and marlytes, blue and green below, gray, brown, and red above, 1,220 feet, 



(the lower 250 found only in deep borings.) 



Upper Silurian. 



Niagara, Clinton Epoch. — Cream to salmon-colored, semi-crystalline, crinoidal lime- 

 stone, 10 to 40 feet. 

 Niagara Epoch. — Shales, 60 to 100 feet, overlaid by buff and blue arenaceous 



and magnesian limestones, 90 to 180 feet. 

 Salina Epoch. — Limestones, with beds of gypsum, 1 to 16 feet. 

 Lower Helderberg. — " Waterlime " group: gray and yellow, coarse-grained and 



massive limestones, 70 to 100 feet. 

 Oriskany, Oriskany Epoch. — Coarse saccharoidal sandstone, 3 to 10 feet. 



Devonian. 



Corniferous, Corniferous Epoch. — Buff massive limestone, 15 to 100 feet. 

 Hamilton, Hamilton Epoch. — Bluish marly limestone, 10 to 20 feet near Sandusky, 

 elsewhere wanting. 

 Genesee Epoch. — Black, bituminous "Huron" shale, with numerous large 

 calcareous concretions, 250 to 330 feet. Partly Portage ? 



{ "Erie " green, gray, and blue shales, with few thin lay- 

 Chemung, Portage Epoch. — J ers of sandstone and limestone: 1,000 feet in the eastern 

 Chemung Epoch. — 1 counties, 500 to 400 in the central ones, and thinning 

 [ southward until no longer recognized. 



Carboniferous. 



Subcarboniferous, Lower. — " Waverly " shales and sandstones; in the northern 

 counties, 320 feet; 640 feet, on the Ohio River. 

 Upper. — " Maxville " limestone, 10 to 20 feet. 

 Carboniferous, Millstone Grit Epoch. — Conglomerate and sandstones, 10 to 130 feet. 

 Coal- measures. —Shales, sandstones and limestones, with bands of iron oro 

 and twelve workable seams of coal, 2,000 feet. 



3. Michigan {Lower Peninsula) Section. 



Lower Silurian. 



Primordial. — No formation certainly identified. 



Canadian. — " Lake Superior" sandstone, mottled, reddish, or dark and shaly, at 



Sault St. Mary, 18 feet; more to the westward, 250 feet. 

 Trenton, Trenton Epoch. — Blue argillaceous limestone, with shale, 30 feet 



Cincinnati Epoch. — Argillaceous limestone, bluish-gray below, 18 feet or 



more. 



Upper Silurian. 



Niagara, Clinton Epoch. — Argillaceous and calcareous limestones, 51 feet. 

 Niagara Epoch. —White and gray limestones, 97 feet. 



