456 Beviews — Doll/US' s and Montserrat's 



date than the Jurassic, are met with, so that this part of the contiaent 

 appears to have emerged from, the ocean at an early Geological 

 period — all its later formations being apparently the product of 

 subaerial volcanic eruptions. That the great mass of trachytic 

 porphyry which is described as composing the substratum of the 

 entire country south of the dividing range, and the basis on which 

 its vast volcanic mountains are piled up, is itself of volcanic origin, an 

 outflow, or successive outflows, from some great eruptive fissure, 

 admits of little doubt. But our authors seem to entertain much 

 uncertainty as to the mode and period of its formation. Coming to the 

 country direct from the School of Mines of Paris, they are naturally 

 imbued with the doctrine of " Soulevement " so persistently taught 

 there in relation to volcanic rocks in general, and consequently see 

 in this great development of trachytic porphyry, a vast " Souleve- 

 ment," or series of Soulevements, disconnected from the volcanic 

 eruptions, which, however, they cannot but acknowledge, have 

 thrown up enormous cones of cinders, pumice, and ash, in the very 

 midst of these trachytic masses (p. 257). This rock is described 

 as of various tints of brown, grey, and violet, composed of a paste 

 sometimes compact, but generally rough-grained and porous, oc- 

 casionally scorified, containing numerous small crj'^stals of glassy 

 felspar, and a few plates of mica and needle-like crystals of horn- 

 blende, a description tallying with the ordinary varieties of trachyte, 

 as seen in the Mont Dore and Cantal. This rock is accompanied by 

 eqvially vast accumulations of its appropriate pumiceous conglo- 

 merates. Basalt also appears at several points on a large scale, 

 together with its special augitic conglomerates, beds of scorias, 

 lapilli, etc., and these are often inter stratified with the pumice-tuffs 

 belonging to the feldspathic series. 



The most prominent and most interesting feature of the geology 

 of this country consists undoubtedly in the train of prodigious 

 volcanic cones which stud the western slopes and shore, many 

 extinct — not a few recently, or still, in active eruption. The view 

 of a portion of this range, as seen from the sea due south of 

 Guatemala, given in the illustrations to this volume, is very 

 striking ; though allowance must, we presume, be made for some 

 slight exaggeration in this as well as some other views of the angle 

 of slope of the outlines of these lofty and very regular sugar-loaf- 

 shaped cones. Some of these our authors ascended, generally 

 finding a crater, often of large dimensions, at the summit; some 

 beiug perfectly at rest, others — especially those whose recent 

 eruptions are recorded — discharging volumes of acid and sul- 

 phurous vapour from crevices (fumaroles) . We have not space to 

 dwell long on these interesting formations, but will shortly re- 

 capitulate the chief examples described by our authors. Beginning 

 at the Bay of Fonseca, in lat. 13°, we have first the shattered cone 

 of Coseguina, which, during the tremendous eruption of 1835, lost 

 probably a full half of its height, the upper portion being blown 

 into the air by a series of terrific explosions which lasted from the 

 20th January to the end of the following month, and were heard at 



