AMERICA THE OLD WORLD. 
23 
or two thousand feet above the level of the sea, 
these are nevertheless the first mountains that 
broke the uniform level of the earth’s surface and 
lifted themselves above the waters. Their low 
stature, as compared with that of other more lofty 
mountain-ranges, is in accordance with an in- 
variable rule, by which the relative age of moun- 
tains may be estimated. The oldest mountains 
are the lowest, while the younger and more re- 
cent ones tower above their elders, and are usu- 
ally more torn and dislocated also. This is easily 
understood, when we remember that all moun- 
tains and mountain-chains arc the result of up- 
heavals, and that the violence of the outbreak 
must have been in proportion to the strength of 
the resistance. When the crust of the earth was 
so thin that the heated masses within easily broke 
through it, they were not thrown to so great a 
height, and formed comparatively low elevations, 
such as the Canadian hills or the mountains of 
Bretagne and Wales. But in later times, when 
young, vigorous giants, such as the Alps, the 
Himalayas, or, later still, the Rocky Mountains, 
forced their way out from their fiery prison- 
house, the crust of the earth was much thicker, 
and fearful indeed must have been the convul- 
sions which attended their exit. 
The Laurentian Hills form, then, a granito 
range, stretching from Eastern Canada to tho 
