274 REACTION OF THE INTERIOR OF THE EARTH 



presence of craters of elevation and eruption, of lavas, 

 scoriae, pumice, and obsidians, are characterised as vol- 

 canoes once active, but which had become extinct prior 

 to traditional or historic evidence. Unopened trachytic 

 cones and domes, or unopened long trachytic ridges, 

 as Chimborazo and Iztaccihuatl are excluded. Yon 

 Buch, Charles Darwin, and Friedrich Naumann employ 

 the word volcano with a similar limitation. I term 

 " still active volcanoes" those which, when viewed in close 

 proximity, still show signs of activity in a greater or less 

 degree, and of which some have also had in recent 

 times great and well-attested eruptions. I have pur- 

 posely said " when viewed in close proximity," as this 

 last is a very important condition ; for many volcanoes 

 have had their still-subsisting activity denied because, 

 when viewed from the plain, the thin vapours which 

 at a great height rise out of the crater are not seen. 

 Thus, at the time of my American journey, it was even 

 denied that Pichincha and the great volcano of Mexico, 

 Popocatepetl, were still burning ! although an enter- 

 prising traveller, Sebastian Wisse ( 40 ), counted in the 

 crater of Pichincha, around the great cone of eruption, 

 seventy still burning openings or " fumaroles, " and, 

 being engaged in measuring a base-line at the foot of 

 Popocatepetl, in the Malpais del Llano de Tetimpa, I 

 myself witnessed a very distinct eruption of ashes from 

 that volcano. ( 401 ) 



In the New Granada and Quito line, about twice the 

 length of the chain of the Pyrenees, and in which ten 

 out of 18 volcanoes are still burning, we may point out 

 four smaller groups or subdivisions. Proceeding from 

 north to south, these are, the Paramo de Kuiz and the 



