388 SEE— THE NEW THEORY OF EARTHQUAKES [November 15, 



VIII. " The continents and oceans had their general outHne or form 

 defined in earhest time. This has been proved with regard to North America 

 from the position and distribution of the first beds of the Lower Silurian — 

 those of the Potsdam epoch. The facts indicate that the continent of North 

 America had its surface near tide-level, part above and part below it (p. 196), 

 and this will probably be proved to be the conditions in Primordial time of 

 the other continents also. And, if the outlines of the continents were marked 

 out, it follows that the outlines of the oceans were no less so." 



The three other conchisions announced by Dana are of less in- 

 terest, and need not be quoted here. 



(B). The following deductions (p. 732) regarding the positions 

 of the rehefs are of high interest : 



" I. The situation of the great mountain chains, mainly near the borders 

 of the continents, does not indicate whether the elevating pressure acted 

 within the continental or oceanic part of the earth's crust. But the occurrence 

 between the principal range and the seacoast of the larger part of the vol- 

 canoes (and, therefore, of the profound and widely-opened fractures) of 

 these borders, of the most extensive metamorphic areas, and of the closest 

 and most numerous plications of the strata, as so well shown in North 

 America, are sufficient evidence that the force acted most strongly from the 

 oceanic direction." 



" 2. The relation between the extent of the oceans and the height and 

 volcanic action, etc., of their borders proves that the amount of force in 

 action had some relation to the size and depth of the oceanic basin. The 

 Pacific exhibits its greatness in the lofty mountains and volcanoes which 

 begirt it." 



"3. In such a movement, elevation in one part supposes necessarily sub- 

 sidence in another; and, while the continental was the part of the crust which 

 was elevated, the oceanic was the subsiding part." 



In connection with the theory that the mountains are formed by 

 the expulsion of lava from beneath the sea, through the operation of 

 world-shaking earthquakes, these early views of Dana are of great 

 interest. But in other respects he was led astray by the doctrine 

 of the secular refrigeration of the globe ; for he says that " no other 

 cause presents itself that can comprehend in its action the whole 

 globe and all time." He thus speaks as if the entire globe were 

 shrinking, whereas local changes only are occurring, and these 

 always near the sea. Dana's view that " the pressure of the sub- 

 siding oceanic portion has acted against the resisting mass of the 

 continents ; and thus the border between them has become elevated, 

 plicated, metamorphosed and embossed with volcanoes," is alike 



