HuTTON. — On the Formation of Mountains, xxxiii 



generally associated with metamorpliic and granitic rocks. These have been 

 formed by heavy argillaceous deposits, causing subsidence and contortion, 

 which have been subsequently elevated by the superposition of calcareous 

 beds. The second kind, of which the Andes may be taken as the type, are 

 composed of nearly horizontal strata, generally associated with volcanic rocks.* 

 These have been formed by the upward pressure of the underlying rocks 

 caused by the subsidence of adjoining areas, and owe their height partly to 

 this upward pressure, but often in great part to the overflowing of the super- 

 heated rocks on the surface. 



There is, however, one other point that has still to be taken into account. 

 If we calculate the mass of the ocean we shall find that it is sufiicient, if the 

 surface of the earth were level, to cover it entirely to a depth of at least two 

 miles. Now, if it is true that the earth has been formed by the slow conden- 

 sation of gaseous matter, we can see no possible reason why any of the gaseous 

 materials should be confined in the interior solidifying portions, and by their 

 attempts to escape cause eructations, or bubbles that could raise any part of the 

 solid mass more than two miles high. In other words, I do not see how there 

 could be any boiling or swelling up sufficient to form land above the surface of 

 the ocean. If then there was no land in this primaeval ocean for denudation 

 to act upon, what was it that first disturbed the equilibrium of the crust and 

 so led the way to those stupendous changes that we know have since taken 

 place % But one answer can I think be given to this question, viz., the origin 

 of life. Chemists are agreed that carbonate of lime was in solution in this 

 primaeval ocean, and when life, or rather life capable of secreting carbonate of 

 lime, appeared it would abstract this substance out of the ocean and deposit it 

 on particular areas, and thus, by disturbing the equilibrium, would prepare the 

 world to be the habitation for those countless myriads of organised beings 

 which now swarm over it. 



I will hazard one more supposition. Over this primaeval ocean the winds 

 must have swept with great regularity, and currents must have followed in 

 their wake. Now these currents would naturally take two directions, one 

 N.E. and S.W., and the other at right angles to it. If, therefore, we suppose 

 life to have originated at any one point, it would gradually spread in a 

 N.E. and S.W., or N.W. and S.E. direction, and the first calcareous deposits, 

 and consequently the first land, would take these directions also. This would 

 give the direction of other deposits, and although much obliterated by the 

 complications that have since taken place, we can possibly, even now, trace in 

 the directions of our mountain chains some remnant of this primaeval arrange- 

 ment. But this is sheer speculation. 



* See also Darwin "On Volcanic Phenomena in South America." — Trans. G. Soc, 

 2nd Series, V. 601. 



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