PRIMITIVE ROCKS. 171 



to the shores and islands of the Arctic Sea. The western 

 limit or strike of this formation, which I have traced for 

 more than 1,400 geographical miles, has a general course 

 of north 30° W., its rhumb line, consequently, inclines 

 slightly towards the axis of the Rocky Mountains, and 

 the intercepted space grows narrower towards the north. 



On the other hand, the Apalachian chain, running 

 parallel to the Atlantic coast for a thousand miles up to its 

 termination in the Shickshock and Notre Dame Mountains 

 of the promontory of Gaspe, and having a direction of 

 north 46° E., diverges from the Rocky Mountain axis at 

 an angle of 72°. These are the three chief pyrogenous 

 systems of North America, the Ozark Hills being of lesser 

 account, and coinciding, as has been said above, in di- 

 rection with the Alleghanies. 



The middle belt of primitive rocks may, both from its 

 position and diagonal direction, be distinguished as the 

 intermediate primitive or hypogenous formation. Its altitude 

 nowhere entitles it to the appellation of a mountain chain. 

 Its hypogenous rocks, which are chiefly granite and gneiss 

 associated with trap, scarcely rise above the mean eastern 

 slope, and do not present acute peaks or continuous ele- 

 vated ridges. They exhibit generally rounded or dome- 

 shaped summits, or form oblong eminences, which are sepa- 

 rated from one another by narrow inclined valleys. Most of 

 these valleys, and the larger ones without exception, are 

 occupied by lakes, which are often deep ; and the proportion 

 of water in the district is very great, probably considerably 

 exceeding that of the dry land. 



The rivers that traverse the intermediate primitive belt 



any of the current opinions : I would therefore be understood to use 

 the terms " primitive," " hypogenous," and " metamorphic," as desig- 

 nations of the rocks so called by geologists, and not as exponents of 

 theories. 



