31-i T/te Position of the Cincinnati Group. 



The Post Tertiary may be estimated at 1,000 feet, including the 

 drift sand and gravel. 



The total thickness of the strata which have been deposited since 

 the deposition of the Cincinnati rocks is thus shown to be 57,816 feet, 

 or nearly eleven miles. The total depth of the geological column, as 

 thus represented, is nearly twenty-seven miles. All of which will 

 more readily appear by the following tabular statement : 



A Tabular View of the Maximum Thickness of the Fossilltferous Forma- 

 tions, their Divisiom, and Groups, as Found in the Carefully Explored 

 Parts of Noiih America, beginning with the Lowest Group, and Ascend- 

 ing through the Series. 



1 fit. Metamorphic : 



Feet. 



Laurentian series from the Eozoon Canadense 16,500 



Huronian series 20,000 



2d. Lower Silurian : 



St. JolinsGroup , 3,000 



Potsdam ._. 19,000 



Calciferous 1,839 



Quebec .- 12,145 



Chazy 300 



Black river and Birdseye .'i,,500 



Trenton 2,500 



Utica Shales • 400 



Cincinnati Group 2,000 



8d. Upper Silurian : 



Oneida Conglomerate and Medina sandstone 1,650 



Clinton Group 1,625 



Niagara Group 1,700 



Onandaga Salt Group 1,000 



Lower Helderberg 2,000 



4th. Devonian : 



Orisl<anj'- sandstone 300 



Upper Helderberg 1,225 



Hamilton Group 1 150 



• Portage Group 1 700 



Chemung Group 3 20O 



Catskill Group 7 660 



5th. Carboniferous : 



Lower Carboniferous * 7 636 



Carboniferous conglomerate 1 400 



Coal measures 14 570 



