216 REACTION OF THE INTERIOR OF THE EARTH 



inclined strata : but frequently no trace of this circular ram- 

 part can be perceived ; and the volcano, which is not always 

 of a conical form, rises immediately from the table land like 

 the ridge-shaped volcano of Pichincha, at the foot of which 

 the town of Quito is built. 



As the nature of rocks, or the mixture or association 

 of simple minerals which unite to form granite, gneiss, and 

 mica slate, trachyte, basalt and dolerite, is wholly indepen* 

 dent of our present climates, and is the same in all latitudes 

 and all regions of the earth; so also we see that every, 

 where in inorganic nature the same laws regulate the super- 

 position of the strata composing the crust of the globe, their 

 mutual penetrations, and their elevation by the agency of 

 elastic forces. In volcanoes especially, the identity of form 

 and structure is peculiarly striking. The navigator amongst 

 islands of remote seas, where new stars replace those on 

 which he has been accustomed to gaze, and where he finds 

 himself surrounded by palms and other unfamiliar forms of 

 an exotic flora, yet recognizes in the features of inorganic 

 nature which characterise the landscape, the forms of 

 Vesuvius, of the dome-shaped summits of Auvergne, of 

 the craters of elevation of the Canaries and the Azores, and 

 of the fissures^pf eruption of Iceland. The analogies thus 

 noticed receive a still wider generalization when we view the 

 attendant satellite of our planet. The maps of the moon, 

 which have been traced by the aid of powerful telescopes, 

 exhibit to us a surface devoid of air and water, abounding in 

 vast craters of elevation surrounding or supporting conical 

 eminences ; thus clearly evidencing the effects of the reaction 

 of the interior of the moon upon its exterior ; a reaction fa- 

 voured by the feebler influence of gravitation at the surface. 



