294 COSMOS. 



* 



configuration. All that we know regarding- this subject re- 

 solves itself into this one point, that the active cause is sub- 

 terranean ; that continents did not arise at once in the form 

 they now present, but were, as we have already observed, in- 

 creased by degrees by means of numerous oscillatory elevations 

 and depressions of the soil, or were formed by the fusion of 

 separate smaller continental masses. Their present form is, 

 therefore, the result of two causes, which have exercised a con- 

 secutive action the one on the other : the first is the expression 

 of subterranean force, whose direction we term accidental, 

 owing to our inability to define it, from its removal from with- 

 in the sphere of our comprehension, while the second is derived 

 from forces acting on the surface, among which volcanic erup- 

 tions, the elevation of mountains, and currents of sea water 

 play the principal parts. How totally difTerent would be the 

 condition of the temperature of the earth, and, consequently, 

 of the state of vegetation, husbandry, and human society, if 

 the major axis of the New Continent had the same direction 

 as that of the Old Continent ; if, for instance, the Cordilleras, 

 instead of having a southern direction, inclined from east to 

 west ; if there had been no radiating tropical continent, like 

 Africa, to the south of Europe ; and if the Mediterranean, 

 which was once connected with the Caspian and Red Seas, 

 and which has become so powerful a means of furthering the 

 intercommunication of nations, had never existed, or if it had 

 been elevated like the plains of Lombardy and Cyrene 1 



The changes of the reciprocal relations of height between 

 the fluid and solid portions of the earth's surface (changes 

 which, at the same time, determine the outlines of continents, 

 and the greater or lesser submersion of low lands) are to be 

 ascribed to numerous unequally working causes. The most 

 powerful have incontestably been the force of elastic vapors 

 inclosed in the interior of the earth, the sudden change of tem- 

 perature of certain dense strata,* the unequal secular loss of 



* De la Beclie, Sections and Views illustrative of Geological Phenome- 

 na, 1830, tab. 40 ; Charles Babbage, Ohservations on the Temple of 

 Serapis at Pozzuoli, near Naples, and on certain Causes which may 

 produce Geological Cycles of great Extent, 1834. " If a stratum of sand- 

 stone five miles in thickness should have its temperature raised about 

 100°, its surface would rise twenty-five feet. Heated beds of clay 

 would, on the contrary, occasion a sinking of the ground by their con- 

 traction." See Bischof, Wdrmelehre des Innern unseres Erdkorpers, s. 

 303, concerning the calculations for the secular elevation of Sweden, on 

 the supposition of a rise by so small a quantity as 7° in a stratum of 

 about 155,000 feet in thickness, and heated to a state of fusion. 



