Central American Geology. 42S 



lake of Nicaragua is one of these, and he observes that if volcanic 

 activity has opened out the way for the piercing of the canal such 

 an agent must be regarded as a formidable auxiliary. He goes 

 DM to describe in considerable detail the function of these fractures, 

 which are transverse to the general alignment of the several volcanic 

 ranges, and insists upon it that the four fractures of the first class, 

 viz. those which effect the dislocation of each of the four volcanic 

 ranges, mark the sites of the greatest instability. 



The author has no doubt as to the correctness of the above 

 generalization, but there are further conclusions of considerable 

 interest, though not so absolutely certain. The volcanic activity 

 of this region appears to be undergoing a change of position, and 

 this too in a definite direction. He quotes Suess in support of this 

 view, who considered that this shifting of position is always taking, 

 place in the direction of the Pacific. After going into the history 

 of eruptions and earthquakes, he concludes that in the course of a few 

 centuries since the Spanish conquest " the preponderance has passed 

 from Guatemala to San Salvador ; and, as to Nicaragua, the difference- 

 with the aforementioned states is growing less. If we add that 

 in Mexico volcanic activity has immensely diminished since the 

 Quaternary period, that in the preceding periods it attained its 

 maximum much further north, along the coasts of the United States 

 of America, we cannot fail to be most strongly struck by the 

 significance of the preceding enumerations." If we proceed to 

 apply this principle of shifting to the great transverse faults, 

 which break the continuity of the volcanic chains, we perceive 

 the same movement en echelon from north-west to south-east. "The 

 transverse fracture of Guatemala has but one active volcano in its- 

 neighbourhood, viz. Fuego : it is a seismic line of diminishing 

 intensity ; its lake has scarcely a volcanic appearance ; it is a fire- 

 place on the road to extinction. Fonseca, with its girdle of active 

 volcanoes, has had its great catastrophe in 1835 : whether or no that 

 is likely to be the last, it is a fire-place in full activity. The lake 

 of Nicaragua is also an active fire-place ; it is perhaps, as Fuchs 

 asserts, the principal fire-place in Nicaragua ; but, violent though, 

 it has been, the eruption of 1883, compared with that of Coseguina, 

 is but an abortive eruption. It is a warning ; the catastrophe has yet 

 to come." 



With such a possibility in view Professor Bertrand asserts that 

 the dangers which menace this region are by no means of a vague 

 nature. Again, he insists that the line of Nicaragua is one of the 

 lines of weakness and instability of Central America, the lowering 

 of the platform being due to a transverse volcanic fracture ; the 

 same cause which creates apparent facilities for the cutting of the 

 canal creates also a lasting danger. "What has happened on the 

 homologous site of Fonseca indicates the nature of this danger, not 

 with absolute certainty, but with the chance of fulfilment at no 

 distant period. He then proceeds to point out the possible results 

 on works such as an interoceanic canal would require. What with 

 eruptions, earthquake shocks, and seismic waves, these would have. 



