316 Hutt—On the Geological Age of the North Atlantie Ocean. 
view that, while the originating lands of the Carboniferous sediments lay in the 
position of the Western Atlantic, the interior continental regions of North Ame- 
rica, extending into the region of the Rocky Mountains, were occupied by the 
waters of the then ocean; so that it is not overstating the case to say that the 
relative positions of land and sea have been reversed since the Carboniferous 
period. (See diagram, Plate VIIL., fig. 2.) 
(4) Later Conditions of the Atlantic and Bordering Areas——Having thus endeavoured 
to establish the proposition that, down to the close of the Carboniferous period at 
least, the area of the Atlantic was mainly in the condition of land, while the 
adjoining regions bordering it on either side were mainly in the condition of sub- 
merged areas, it may be asked—When did the oceanic condition of the North 
Atlantic area actually set in? When, in other words, was this part of the 
northern hemisphere first overspread by ocean water ? 
Replying to this question, it may be stated that in all probability the formation 
of the Atlantic Ocean, as we see it to-day, was the work, not of one, but of succes- 
sive terrestrial movements. At the same time we have very clear evidence that, 
on the western side of the area here embraced, the formation of the Atlantic 
Ocean on the one hand, and of the American continent on the other, commenced 
immediately after the Carboniferous epoch itself. 
The determination of the period of the uprise of the Alleghanies serves as the 
key to this problem. It must be obvious to everyone who considers the structure 
of the Alleghany range, and the relations of its flexures to the outline of the 
American continent, that there is a close relationship between the two. But, 
besides this, there is (to my mind) a very evident connexion between the position 
of the Alleghany axis and the line of the deep trough which runs along the eastern 
shore of North America, and which is overspread by the waters of the Gulf Stream. 
Were the bed of the North Atlantic Ocean laid dry it would be found to consist of 
three main features—as pointed out by the Rev. Dr. Haughton—a central ridge, 
bordered on either side by deep depressions. What, we may ask, do these features 
indicate in the history of its early formation ? I need not here repeat the argu- 
ments which go to show that the uprise of the Alleghanies and of Central Ame- 
rica dates from an epoch intermediate between the Carboniferous itself on the one 
hand and the Triassic on the other.* Generally speaking, the great flexuring 
and uprising of this range of mountains, extending physically from Alabama to 
Newfoundland, marks the boundary in time between the Paleozoic and Mesozoic 
epochs. Previous to the commencement of these terrestrial movements the Car- 
boniferous beds extended far beyond the present limits of the American continent, 
and out into the region now submerged beneath the Atlantic waters. Beyond this 
* This is proved by the position of the Triassic beds of Richmond, Virginia. See Dana, ‘‘ Manual 
of Geology,” p. 403. 
