84 PROCEEDINGS OF THE CANADIAN INSTITUTE. 



The elevation of the summit of this dome was about 1300 feet above 

 the water. 



This island immediately upon its emergence from the bed of the 

 ocean gave rise to wave action, and the work of erosion or denudation 

 began. With increasing elevation the land kept ahead of the ocean, 

 but around the base of the island the beds of the Niagara period were 

 being formed out of the waste material. If this increase in the eleva- 

 tion had not taken place the whole island would soon have been 

 reduced to a uniform level and the Niagara rocks the only ones formed 

 at that point. Another slight increase in height and a portion of the 

 newly formed Niagara beds was brought to the surf^ice to be subjected 

 to the tear and wear of the waves and to contribute toward the build- 

 ing of the Lower Helderberg formations in the same manner as the 

 Nashville and Trenton beds have been levied u])on to construct them. 

 At the close of the Lower Helderberg the island now considerably in- 

 creased in size but lower in elevation and more rounded off than when 

 it first appeared seems to have received a little more elevation, and 

 the Helderberg sea bottom became dry land. In this condition things 

 appear to have remained stationary for a long period until the whole 

 territory took a plunge into the ocean again preparatory to receiving 

 the beds of Black shale and the subcarboniferous beds with which the 

 greater part of the States of Kentucky, Tennessee and northern Ala- 

 bama ai'e overlaid. 



These beds appearing again, the age of coal or the true carboniferous 

 period began. Without discussing the origin of coal we may accept 

 the fact that the state of affairs necessary for coal production existed 

 long enough to form a body of material over 600 feet in thickness in 

 the Cumberland Tableland. 



This coal forms part of the great Appalachian coal-field which 

 stretches all the way from Pennsylvania to Georgia and Alabama, 

 and extends almost clear across the latter State to the boundary of 

 Mississippi with an extension of subcarboniferous beds into that 

 State. The whole of the western margin of this field is very much 

 broken, and fringed with detached outliers scattered along its boundary. 

 Many of such outliers exist in the State of Kentucky standing in the 

 midst of subcarboniferous protean beds. In northwestern Kentucky 

 there is an extensive area covered with coal-beariiiff rocks which have 



