220 



PALEOZOIC TIME. 



Where fullest developed in New York, the Medina group includes four divisions, as 

 follow : — 



4. Red marl or shale, and shaly sandstone, resembling No. 2, below; banded, and 

 spotted with red and green. 



3. Flagstone, — a gray, laminated quartzose sandstone, called " gray band." 



2. Argillaceous sandstone and shale, red, or mottled with red and gray. 



1. Argillaceous sandstone, graduating below into the Oneida conglomerate. 



In the Genesee section (Fig. 397), the strata 1 and 2 correspond to 2 and 3 of these 

 divisions; and the Niagara section contains 2, 3, and 4. 



The Oneida Conglomerate is the surface rock in Oneida and Oswego counties, N. Y. 

 It is here 20 to 120 feet thick, but thins out to the eastward, in Herkimer County. The 

 Esopus millstones are made of it. 



In East Tennessee, the rock is a hard, whitish, thick-bedded sandstone, 400 feet thick, 

 partly a conglomerate, and in many places filled with Scolithus (fillings of worm-bor- 

 ings). 



The Medina beds spread through western New York west of Utica. In East Ten- 

 nessee, in White Oak Mountain, they are 400 to 500 feet thick. In Canada, they occur, 

 south of the St. Lawrence, over a few areas east and northeast of Lake St. Peter. 



In Ohio, a few feet of shales, at the top of the Cincinnati Group, have the red color 

 and sandy texture of the Medina, though to a less degree than at its typical localities ; 

 but no characteristic fossils of that age have yet been found in them. (Orton.) In 

 southern Indiana, similar beds contain Cincinnati group fossils, up to the very line of 

 junction with the Clinton. (Bradley.) 



2. Clinton Epoch. 



The sandstone of the Clinton epoch in New York is often quite hard ; and much of it 

 has the surface uneven from knobby and vermiform prominences, some of which are 

 due to Fucoids. 



a. Interior Continental basin. — On the Genesee (see Fig. 396, p. 219), the Clinton 

 group consists of, — 



(1.) 24 feet of green shale, of which the lower part is shaly sandstone and the upper 

 part an iron-ore bed; (2.) 14 feet of limestone, called Pentamerus limestone, from a 

 characteristic fossil; (3.) 24 feet of green shale; (4.) 18|feetof limestone, called the 

 upper limestone. 



On the Niagara (see section, Fig. 397, p. 219), there is only a shale 4 feet thick, 

 without the iron-ore, overlaid by a limestone stratum 25 feet thick, — this limestone 

 corresponding to the three upper divisions, and its upper 20 feet to the upper limestone. 

 To the eastward, in Oneida, Herkimer, and Montgomery counties, the rock is 100 to 

 200 feet thick, and includes no limestone, though partly calcareous. The group con- 

 sists of shale and hard grit or sandstone,in two or more alternations, along with two 

 beds of the lenticular iron-ore. The flattened grains making up this ore are concretions 

 like those of an oolite. Near Canajoharie — which is not far from its eastern limit — 

 the formation has a thickness of 50 feet. In the town of Starkville, Herkimer County, 

 the rock contains a good bed of gypsum. In the southern part of Herkimer County, 

 the beds are separated from the Hudson River shales by only a small thickness of the 

 Oneida conglomerate. 



In Ohio and Southern Indiana, the Clinton group, 10 to 60 feet thick, is recognized by 

 its fossils, overlying the shaly limestone of Cincinnati. In Wisconsin, there is a bed of 

 lenticular iron-ore, 6 to 10 or even 15 feet thick, which is referred to the Clinton epoch. 



North of Lake Huron, the Clinton beds occur along the Manitoulin Islands, Drum- 

 mond Island, and 20 miles to the westward. 



b. Appalachian region. — In Pennsylvania, Professor H. D. Rogers divides the rocks 

 into (1) a lower slate,which at Bald Eagle Mountain is 700 feet thick; (2) iron -sand- 

 stone, 80 feet in the Kittatinny Mountain ; (3) upper slate, 100 to 250 feet; (4) lower 

 shale, 100 to 250 feet; (5) ore sandstone, 25 to 110 feet; excepting the last, these strata 



