J^.OSS — ON PARALLEL LINES OF ELEVATION. 139 



equator nearly perpendicularly, it follows that withiri me fifty 

 degrees on each side of ihe equator the remaining lines of elevation 

 will be east and west, or north and south (approximately). It will 

 be remembered that our own Province is one illustration : the four 

 systems of lines of elevation which 1 have indicated as beino; found in 

 Nova Scotia have^'ihese directions : and any country in ihe world 

 (within fifty deg. of the equator) will constitute another. Id the 

 Polar regions, and their vicinity, it is for an obvious oeason 

 impossible to assign any definite directions to the Mountain ranges 

 generally. 



From what has been said it appears that the structure of a 

 country — the stratification of its rocks — depends chiefly apon the 

 mode in vrhich the various systems of parallel lines of elevation 

 intersect each other there. The region of the Alps being at once 

 specially welj known to geologists, and specially remarkable in itself, 

 is a good illustration. The lines of zones ISTos. 2, o, 4-, 5. r'md 6j 

 can be distinctly made out ; hence its complicated structure. 



It is evident that the various zones and subzones of elevation 

 largely affect the; currents of the ocean, and of the atmosj^here ; 

 thereby determining the denudation and formation of rock, and large- 

 ly affecting the distribution of plants and animals. Thus the Atlantic 

 equatorial current, being finally stopped in its vfestwardl;^' progress 

 by zone No. 1, forms a. great current known as the Gulf Stream, 

 which bears the vfarm waters and some of the organic productions 

 of the tropical regions along the west coast of Europe to the Polar 

 Regions beyond Spitzbergen. If v>^e compare the Sahara of Africa 

 with the silvas of the basin of the Amazon, vfe see the effect pro- 

 duced by having a zone of elevation on the eastern side of a tropical 

 country thus intercepting the moisture of the prevailing winds. 



The intersections of several subzones sometimes form -basins 

 which have no outlet to the sea for their drainage, and therefore 

 form lakes, which, since their waters are carried off only by eva- 

 poration, and thus leave their salts behind them, are necessarily 

 salt. The most important basin of this kind is in the greatest sub- 

 continent — Asia-Europe — and has an extent about equal to Europe, 

 the United States, or the Dominion. The more important lines of 

 elevation, especially when they have a direction approximately east 



