The American Geologist. JuIy> 1903 - 
lake Michigan from north to south, skirts the southern mar- 
gin of the Michigan coal-basin, nearly rejoicing its former 
line in Ontario county, on the east, while to the west it runs 
in a narrow line broken by the northern edge of the Illinois 
coal-field and is ultimately lost under the later formations in 
the northwest. 
Another branch line of outcrop runs southward through 
Indiana along the west slope of the Cincinnati arch, and cross- 
ing the Ohio river at the Falls, into Kentucky, reaches nearly 
the middle of that state, where it comes to an end.* 
Northeastward from New York the Corniferous limestone 
may be traced intermittently through Vermont, into Canada, 
indicating an undefined extension in that direction, while is- 
olated outcrops in the southwest, as in Missouri, prove its 
continuance at least so far underground. Westward, however, 
its special characters are lost and it becomes merged in the 
mass of limestone of w T hich, in that region, the Devonian sys- 
tem altogether consists. 
The Great Southern Uplift. — Upon the maps I have at- 
tempted, perhaps rashly, to outline the great features of south- 
ern Appalachia according to the best data within reach, with 
the purpose of showing the continuity (not altogether uni- 
form) of the series of movements which were there taking 
place and which resulted in important changes in the positions 
and relations of the Jand and water areas. The maps will fur- 
ther show that this series was inaugurated early in the Silurian 
era, through which it continued interruptedly, reaching its 
maximum during the succeeding era. 
It should be borne in mind that, at the close of the Ordo- 
vician era, no land existed from the mainland in the east far 
away to the westward, and that disturbances then ensuing 
raised the Cincinnati arch and produced the islands of Cincin- 
nati and Nashville, at the same time so elevating the eastern 
land in some places as to provide a source for the materials 
of the Medina sandstone. Granting that this was the whole 
extent of the movement, it- is obvious that the Appalachian sea 
underwent thereby a considerable change and that its eastern 
portion was separated from the main ocean and converted into 
a wide channel running from the northeast to the southwest 
* Geol. Survey or' Kentucky, vol. iii, p. 394. 
