222 REACTION OP THE INTERIOR OP THE EARTH 



of Quito communicate by numerous narrow channels. The 

 fish of these rivulets multiply by preference in the obscurity 

 of the caverns ; and when the whole mass of the volcano is 

 powerfully shaken by the earthquake shocks, which, in 

 the Andes, always precede eruptions, these subterranean 

 caves are suddenly opened, and water, fishes, and tufaceous 

 mud, are all ejected together. It was by this singular phse- 

 nomenon that the inhabitants of the plains of Qui'o were 

 made acquainted with the little fish which they call Prena- 

 dilla, Pimelodes cyclopum. ( 22 ) When, in the night of 

 the 19th of June, 1698, the summit of the Carguairazo 

 (18000 French feet in height) fell in, leaving two immense 

 peaks of rock as the sole remains of the wall of the crater, 

 masses of liquid tufa, and of argillaceous mud ( lodazales ) , 

 containing dead fish, spread themselves over and rendered 

 sterile a space of nearly two square German miles. The 

 putrid fevers which seven years before prevailed in 

 the mountain town of Ibarra, north of Quito, were attri- 

 buted to the quantity of dead fish ejected in like manner 

 from the volcano of Imbaburu. 



Water and mud, which, in the Andes, do not issue from 

 the crater, but from caverns in the trachitic mass of the 

 mountain, cannot be strictly classed among volcanic pheno- 

 mena, in the restricted sense of the expression. Their con- 

 nection with the volcanic activity of the mountain is only 

 indirect, as is that of the singular meteorological pheno- 

 menon to which, in my earlier writings, I have given the 

 name of " volcanic storm." The hot steam which, during 

 the eruption, issues from the crater and mingles with the 

 atmosphere, condenses as it cools, and forms a cloud sur- 

 rounding the column of fire and ashes, which rises to a 



