GEOLOGY AND SCENERY OF NORTHEAST COAST 87 



long battered by the weather of ancient days, and so long 

 and successfully attacked and lowered by streams, that 

 already very early in the earth's history these mountains 

 had been flattened to a relief probably as tamed as that of 

 the great Canadian plateau to-day. It was this old-moun- 

 tain plain, or almost-plain, which formed the nucleus of 

 North America. No one can say as yet, even approximately, 

 how much the old plateau has been affected by the destruc- 

 tion of the millions of years since it was reelevated from 

 beneath the sea, with its mantling load of Cambrian, 

 Silurian, Devonian, and later sediments. Again and again 

 the Basement has been, wholly or in part, alternately above 

 and below sea-level. With each emergence it has lost sub- 

 stance, and with each loss a new physical geography has 

 been developed upon it. 



When a mountain- system is young, its summits are 

 ranged more or less systematically in straight or slightly 

 curved lines joining the crests of the various ranges. When 

 the system is very old, that is, worn down flat by age-long 

 wasting, these same trends may still be recognized in the 

 structure of the mountain-roots. A normal range owes its 

 existence, not so much to simple uplift of the earth's crust 

 as to an intense folding and crumpling together of its rock- 

 strata by powerful forces acting tangentially with reference 

 to the curve of the earth and transverse to the axis of the 

 range. If, therefore, the Basement Complex forms the 

 root of an old mountain-system, the natural inquiry arises 

 as to the trend of the rock-bands now visible to the geolo- 

 gist; for these, even in the absence of the long-vanished 

 mountainous relief, will tell the direction of the old ranges 

 and, by implication, the direction of the great compressive 



