^v 





leaf, 



."^^■^^ tie 



^S from 5 



•8 before 

 iieuisdves 



•ftteems. 



pearinga? 



.1 



imbe 



„„tioiiof 

 [r. Srf 



JornllO' 



■i; 



liditv ^a^ 

 probab 



, of * 



for* 



(i 





CilXXVil] convexity of the plain of malpais. 



55 



fig. 89), is quite in accordance with the known laws which 

 govern the flow of lava. 



om 



from JoruUo, would be com 



of heavier and more bulky particles near the cones, and 

 would raise the ground at their base, where, mixing with 



T 



mi 



which is described as covering the lava. 



small c 



'esemble 



five or six small hillocks which existed in 1823 on the 

 Vesuvian lava, and sent forth columns of vapour, having been 



* 



ement 



mentioned 



small dome-shaped masses of lava. The fissures 

 bj Humboldt as of frequent occurrence, are such as might 

 naturally accompany the consolidation of a thick bed of lava, 

 contracting as it congeals ; and the disappearance of rivers 



result 



many 



examples in the old lava currents of Auvergne. The heat of 



Mr 



to have diminished from 

 visited the spot many y( 



after 



temperature 



seems 



from its immense 



thickness may have been enabled to retain its heat for half 



reminded 



a century. 



suppose the lava near the volcano to have been, together 



with 



more 



than 500 feet in depth, we 

 merely assign a thickness which the current of Skaptar Jokul 



some 



Hollow sound of the plain when struck. — Another argument 

 duced in support of the theory of inflation from below, was, 



by the steps of a horse upon the 



. ^ roves nothing more than that the 



materials of which the convex mass is composed are light and 



made 



porous. The sound 



rimbombo 



very commonly returned by made ground when struck sharply ; 

 and has been observed not only on the sides of Vesuvius and 

 other volcanic cones where there is a cavity below, but in 



