in the Geological History of North America. 345 



The Azoic, as has been indicated, has something of a V shape, 

 (or V)i with Hudson Bay between its arms. This succeeding 

 step of progress is the partial development of a larger Y outside 

 of and parallel to the Azoic nucleus. The channels alluded to 

 lie between the two Vs. The bar of the outer Y on the left is of 

 great breadth and made up of several broad parallel bands or 

 ranges of elevations ; that on the right is quite narrow compar- 

 atively, yet also etched in several parallel lines. 



The Mexican Gulf is all that remains of the larger of these 

 channels. Its waters once stretched to the Arctic Sea, and were 

 in early time but the deeper part of the continental ocean. 

 Later, as the ages moved on, there was land to the north, and a 

 line of freshwater lakes along its former course ; and the Gulf 

 reached no higher than the headwaters of the Missouri. Later 

 still, and its limits became more contracted, till now the full- 

 grown continent has but her foot in the salt water. 



The Gulf of St. Lawrence marks the outlet of the other chan- 

 nel, and the Eiver St. Lawrence its course. The great lakes, as 

 well as the smaller lakes north, lie near the limits of the Azoic 

 nucleus within these ancient troughs or depressions; and the 

 largest lake, Lake Superior, is at the junction of the two lines. 



Such was the law of growth. The molecular forces heneath 

 the continent, from the progressive cooling there going on, were 

 not idle, and must have modified the results. But the main 

 action causing the lifting and sinking of the crust and the final 

 gain to the land, proceeded from the directions of the oceans. 

 The inequality in the forces from the two directions, as well as 

 in the form and depth of each oceanic or subsiding area whence 

 the forces mainly came, would necessarily have produced many 

 irregularities in the results, as I have remarked in another place,* 

 and will not now dwell upon. 



The Pacific region has always been true to its own grandeur. 

 The force from that direction not only made the Eocky Moun- 

 tains to rise and a file of lofty volcanoes to light up its waters, 

 (while the most the gentler Atlantic could accomplish was a 

 bending up of the strata into Appalachians, and a baking of some 

 of the beds,) but it also added tenfold the most dry land to the 

 continent ; and even after the tertiary rocks were deposited, it 

 elevated the continental border at least two or three thousand 

 feet — ten times beyond what happened on the Atlantic side.f 



* Amer. Jour. Sci. [2], vol. iii. 



f Whatever doubts may exist as to the cause, there can be none as to the actu- 

 ality of the force on the two sides, the Atlantic and the Pacific. The elevation of 

 the mountains on each border is proof beyond question ; and their relative extent and 

 height is evidence indubitable as to the relative amounts of force exerted. The 

 parallel folds on the Atlantic side show that there it was actually lateral force from 

 the southeast ; and the several parallel ranges on the Pacific side, parallel to the 



SECOND SERIES, VOL. XXII, NO. 66. — NOV., 1856. 



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