475 



bles (lat. 2° 20' north), on the west. The ridge 

 that separates the Rocky Mountains stretches 

 from west to east, towards Lake Superior, be- 

 tween the basins of the Missouri, and that of 

 the Lake Winnipeg and the Slave Lake. We 

 have seen the central Cordillera of Mexico and 

 the Rocky Mountains follow the direction N. 

 10° W., from 25° to 38° of latitude ; the chain 

 from that point to the Polar Seas is prolonged 

 in the direction N. 24° W., and ends in the pa- 

 rallel 69°, at the mouth of the Mackenzie ri- 

 ver*. 



In thus developing the structure of the Cor- 

 dilleras of the Andes from 56° south, to be- 

 yond the arctic circle, we have seen that its 

 northern extremity (long. 130° 300, is nearly 

 61° of longitude west of its southern extremity 

 (long. 69° 40 ') ; this is the effect of the long 

 duration of a direction from S.E. to N.W. on the 

 north of the isthmus of Panama. By the extra- 

 ordinary breadth of the New Continent, in the 

 30° and 60° of north latitude, the Cordillera of 

 the Andes, continually drawing nearer the 

 western coast in the southern hemisphere, is 



* The eastern boundary of the Rocky Mountains lies — 



In 38° latitude 107° 20' longitude. 



40° 108o 30' 



63o 124° 40' 



68o 130° 30 ' 



