CHAPTER V. 
ON THE GEOLOGY 
OF THE UNITED STATES AND THE BUITISll PROVINCES OF NORTH AMERICA. 
GEOLOGICAL .MAP OF NOKTH .AMERICA, — See: FRO.NTISPIECE. 
(Extract from Dr. A. Petermann’s Geofraphisclten MUlheihmgen , Heft 6, in 4“. Gotha, 1855.) 
General sketch of the physical features of North America, — The United States and the British Pro- 
vinces may be divided into three principal regions. 1° the eastern or Atlantic region, 2° the central 
or Rocky mountain region, 3° the western, or the region of the Pacific ocean. These divi- 
sions correspond exactly with the three great geological divisions of this continent. The east- 
ern region is that of the Paleozoic formation, the Rocky mountain region contains especially the 
Secondary rocks, and the western region is that of the Tertiary rocks. The distinctive characters 
of these different divisions of the country are very numerous. 1 shall try to give a sketch of these, 
but first I would call attention to a physical character common to all three, namely, that all the 
mountain chains have a direction from north to south. This direction of north-south is not to 
be understood absolutely; the Alleghanies incline to the east, and the Rocky mountains to the west, 
but these deviations have no influence on the general conformation. 
1°. The eastern or Atlantic region embraces the whole country situated between the Atlantic 
ocean and the gulf of Mexico, and the Prairies or eleAmted plains of the West. The western limit 
of this region may be marked by a line drawn from Eagle Pass, on the Rio del Norte, to Fort 
Washita; from thence to Council-Grove, Council-Bluffs, the sources of the Mississippi, and the north- 
ern (Canadian) Red river. It is bounded on the north by a low range of mountains known by the 
name of the Lawrentine mountains , running from east to west , and forming the dividing ridge for 
the waters flowing into Hudson’s bay and those discharging themselves into the Atlantic ocean and 
the gulf of Mexico. The Lawrentine mountains consist of hills and mountains from 1200 to 2000 feet 
high, and this small elevation prevents them from influencing the northern winds which cross them 
without hindrance, this being one of the chief causes of the extreme cold that prevails in these 
countries. 
Thus bounded , the eastern region embraces all that part of the country actually inhabited and 
cultivated by the white man, including the whole course of the Mississippi, Ohio, Hudson and 
S* Lawrence rivers, and the basins of the Great Lakes. 
The mountains included in this eastern region are : first the Notre Dame mountains in the dis- 
trict of Gaspe, their medium height is 2500 feet and their greatest elevation does not exceed 4000 feet; 
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