512 Revieivs — Richthofen's System of Volcanic Bocks. 



the school of Humboldt, which refuses to acknowledge any mountain 

 mass to have been a volcano, though composed wholly of volcanic 

 rocks, which has not an evident " opening" or crater at its summit, or 

 at least a conical form, or small radiating streams of lava ; nay, even 

 in the case of these, attributes the formation of the cone and crater 

 to ' upheaval,' not to successive eruptions from the same vent. 

 Thus, among other passages in his Cosmos, Humboldt, says (p. 224 

 Sabine's Translation, Ed. 1858) : — 



"We may ascribe to a first fissuring of the deeply disturbed earth- 

 crust, the oldest formation of erupted rocks (often perfectly similar 

 in mineral composition to recent lavas) ; then these fissures, as well as 

 the 'craters of elevation' of later origin, must be looked upon only 

 as volcanic openings tJirougli which erupted masses have flowed, and 

 not as ' volcanos proper.' The principal characteristic of these latter 

 consists in a permanent, or at least from time to time renewed, con- 

 nection between the deep-seated focus, or source of igneous action, 

 and the atmosphere," " The Volcano requires for this purpose a 

 particular kind of framework. Therefore its form-giving or shaping 

 activity is exerted in the upheaval of the ground ; not (as was for- 

 merly believed) in the building up by successive accumulation of 

 scorias and strata of lava deposited one above another," In a sub- 

 sequent passage, referring to the great volcanic development of 

 Western America, he suggests how much remains to be done 

 there by "a. competent Geologist who should devote himself to 

 the mineralogical determination of its trachytes, dolerites, and me- 

 laphyres, and to the discrimination of the originally upheaved mass 

 from the part that has been covered by subsequent eruptions." 

 " Conical or dome or bell-shaped mountains which have never been 

 opened, are to be most carefully distinguished from volcanos, 

 which either now emit, or have at any former period emitted, scorige 

 and lava, like Vesuvius and Etna, or scoria and ashes only, like 

 Pichinca and Cotopaxi" (p. 267, id.). 



It is evident that M. Eichthofen has acted on this hint ; and hence 

 his grand two-fold division of volcanic rocks, into " massive erup- 

 tions," and the products of " volcanos proper," 



It is really time, however, that all these fanciful ideas should be 

 renounced. It is utterly impossible, whether in the writings of 

 these and other Geologists of this school, or in nature, to find any 

 intelligible distinction between volcanic rocks that have issued from 

 fissures, so as to form "massive," or "elongated," or "dome-shaped" 

 mountains, and rocks produced by eruptions from "volcanos proper." 

 It is a miserable thing that such untenable distinctions, couched as 

 they are in vague and confused language indicative of a correspond- 

 ing confusion of ideas, should be taught generally in Mining-schools 

 on the Continent, and, we fear, some of this country also, where 

 Humboldt's Cosmos is still a classical school-book. If these 

 remarks should be considered too strong, let it be remembered that 

 this confusion of ideas as to the origin of volcanic rocks, is not con- 

 fined to a single passage or two of the Cosmos, but pervades the 

 whole of the 350 pages of that work, which treat of "volcanos" 



