436 J. D. Dana—Results of the Eurth's Contraction. 
as early as the beginning of the Silurian. The next on the 
Atlantic border was that of the displacements of the Connecti- 
cut River Sandstone, and the accompanying igneous ejections, 
which occurred before the Cretaceous era:—at least seven 
millions of years, on the above estimate of the length of 
time, after the Appalachian revolution. Thus the lateral pres- 
sure resulting from the earth’s contraction required an exceed- 
i ong era in order to accumulate force sufficiently to 
produce a general yielding and plication or displacement of 
the beds, and start off a new range of prominent elevations 
over the earth’s crust. 
6. System in the mountain-making movements on the opposite 
borders of the North American Continent, and over the 
Oceanic areas. 
A summary of the general system of movements and moun- 
tain-making on the opposite borders of the continent, and over 
the oceanic areas, will, I think, render it apparent that the views 
here sustained have a broad foundation. 
I omit any special reference to the Archwan elevations, and 
also the local disturbances in the Primordial of Newfoundland, 
as well as the facts relating to minor changes of level. 
A. Mountain-making on the Atlantic border. 
accumulations, are not ascertained; probably the extent was 
not less than 20,000 feet. 
(2.) Simultaneously, a permanent anticlinorium was made over 
the Cincinnati region, from Lake Erie into Tennessee, parallel 
with the Alleghanies of Virginia, 250 miles to the northwest. 
(3.) The Acadian region—embracing western Newfoundland, 
St. Lawrence Bay, the Bay of Fundy, and part of Nova Scotia 
and New Brunswick adjoining, and probably the sea southwest 
between St. George’s Bank and the coast of Maine, with also an 
area in Rhode Island—was the course of a great geosynclinal, 
or a series of them, parallel in general direction with that. of 
the Appalachian region; it continued in progress, but wit! 
mountain-making interruptions, and some shift of position to 
‘he eastward, from the Silurian to the close of the Jurassic. 
_ At the close of the Lower Silurian, no general disturbances 
occurred in this Acadian region, so far as is known. In the 
Anticosti seas, or northern part of St. Lawrence Bay, lime- 
