164 OBSEEVATIONS ON 



be found constituting the summits of the highest peaks r 

 Every appearance connected with the structure of Alpine 

 mountains irresistil)ly tends to one conclusion, that they have 

 been pushed up through the superincumbent strata, whose 

 debris are found resting at their bases, or on their flanks. In 

 truth there is such an apparent mutual and intimate con- 

 nexion between those mountainous elevations of the crust, 

 and volcanoes and earthquakes, that it is impossible to re- 

 gard them as distinct phenomena. Earthquakes are more 

 frequent and violent in volcanic countries, and the moun- 

 tains become more gigantic as we approach the torrid zone, 

 the peculiar seat of volcanic action ; and in Europe, let me 

 add, earthquakes are more frequent in tiie vicinity of trap 

 formations than elsewhere. From all this there is reason 

 to conclude, that there are long ranges of subterraneous fire 

 at an immense depth, and that volcanoes are merely the 

 vents through which, as a safety valve, are discharged the 

 elastic vapour and other substances, which, wlien confined, 

 are the cause of earthquakes, and of the upheaving of moun- 

 tains or even continents. 



But to return from this digression. Would it be surpris- 

 ing, if, during a convulsion capable of producing results so 

 tremendous as the breaking up of the earth's crust, a stream 

 of lava should escape through a lateral opening at the base 

 of a mountain newly formed, or that had been thrown up 

 by a previous effort of the same power ? A crater is formed 

 by the gradual accumulation of pumice and ashes ejected by 

 an established volcano ; but I see no reason to doubt that a sin- 

 gle eruption might take place in the manner suggested, which 

 would be sufficient to account for the absence of ail traces 

 of a crater and the want of that conical shape so observable 

 in the mountains of volcanic countries. But that conic shape 

 so decisively volcanic, furnishes no argument that the power 

 which caused it might not, by a different mode of opera- 

 tion, produce those long uniform ridges which constitute the 

 chains of mountains in North America. Humboldt describes 

 Antisan and Pichinca, two volcanoes in the province of 



