266 REACTION OF THE INTERIOR OF THE EARTH 



implying a similar absence of lava in those of Central 

 America. It is true, indeed, that in the majority of 

 cases, as, for example, at the present time in the volcano 

 of Izalco, eruptions of scoriae and ashes are unac- 

 companied by streams of lava; but the descriptions 

 given by eyewitnesses of lava-pouring eruptions in four 

 volcanoes Mndiri, el Nuevo, Conseguina, and San 

 Miguel de Bosotlan militate against the supposition 

 above noticed. ( 392 ) 



I have purposely dwelt at some length on the pecu- 

 liarities of the situation and near vicinity to each other 

 of the volcanoes of the Central American line, in the 

 hope that some geologist, who has made himself 

 thoroughly acquainted with the active European vol- 

 canoes, and the extinct ones of Auvergne or of the 

 Vivarais or of the Eifel, and (which is of the greatest 

 importance) who is competent to describe the minera- 

 logical composition of the rocks according to the re- 

 quirements of the present state of knowledge, might 

 feel himself incited to visit so near and accessible a 

 region. Much still remains to be done there, supposing 

 the traveller to devote himself exclusively to geognostical 

 researches and particularly to the mineralogical deter- 

 mination of the trachytes, dolerites, and melaphyres, 

 to the discrimination of the originally upheaved mass 

 from the part which has been covered over by subse- 

 quent eruptions, and to the discovery and recognition 

 of actual narrow uninterrupted currents of lava, which 

 are too often confounded with accumulations of erupted 

 scoriae. Conical or dome or bell-shaped mountains which 

 have never been opened are to be most -carefully distin- 

 guished from volcanoes which either now emit, or have at 



