GEOGNOSTIC PHENOMENA. __ 203 



liqnid fluids, of hot mud, and of those heated and molten 

 earths which become solidified into crj'stalline mineral masses. 

 Modern geognosy, the mineral portion of terrestrial physics, 

 has made no slight advance in having investigated this con 

 nection of phenomena. This investigation has led us aw y 

 from the delusive hypothesis, by which it was customary for- 

 merly to endeavor to explain, individually, every expression of 

 force in the terrestrial globe : it shows us the connection of 

 the occurrence of heterogeneous substances with that which 

 only appertains to changes in space (disturbances or eleva- 

 tions), and groups together phenomena which at first sight 

 appeared most heterogeneous, as thermal springs, efiusion of 

 carbonic acid and sulphurous vapor, innocuous salses (mud 

 eruptions), and the dreadful devastations of volcanic mount- 

 ains.* In a general view of nature, all these phenomena are 

 fused together in one sole idea of the reaction of the interior 

 of a planet on its external surface. We thus recognize in the 

 depths of the earth, and in the increase of temperature with 

 the increase of depth from the surface, not only the germ of 

 disturbing movements, but also of the gradual elevation of 

 whole continents (as mountain chains on long fissures), of vol- 

 canic eruptions, and of the manifold production of mountains 

 and mineral masses. The influence of this reaction of the 

 Ulterior on the exterior is not, however, limited to inorganic 

 nature alone. It is highly probable that, in an earlier world, 

 more powerful emanations of carbonic acid gas, blended with 

 the atmosphere, must have increased the assimilation of car- 

 bon in vegetables, and that an inexhaustible supply of com- 

 bustible matter (lignites and carboniferous formations) must 

 have been thus buried in the upper strata of the earth by the 

 revolutions attending the destruction of vast tracts of forest. 

 We likewise perceive that the destiny of mankind is in part 

 dependent on the formation of the external surface of the earth, 

 the direction of mountain tracts and high lands, and on the 

 distribution of elevated continents. It is thus granted to the 

 inquiring mind to pass from link to link along the chain of 

 phenomena until it reaches the period when, in the solidifying 

 process of our planet, and in its first transition from the gas- 

 eous form to the agglomeration of matter, that portion of the 

 inner heat of the Earth was developed, which does liot belong 

 to the action of the Sun. 



* [See Mantell's Wo7iders of Geology, 1848, vol. i., p. 34, 36, 105, 

 also Lyell's Princip'es of Geology, vol. ii., and Daubeney On Volcanoes, 

 2d ed., 1848. Part i; , ch. xxxii., xxxiii.] — 7V. 



