1859.] SCROPE CONES AND CEATEES. 525 



the size of the Monte Eosso, the Puy de Come, or the great cones of 

 Lanzarote — hills 600 or 700 feet in height, and of proportionate bulk. 

 What else, then, may we not ask them, can have resulted from the 

 accumulated products of innumerable eruptions repeated for ages from 

 the same vent or its immediate neighbourhood, but just such moun- 

 tainous excrescences as we see in the larger volcanic cones ? And 

 when we find them, on examination, to be composed of beds of lava 

 and scoriae or pumice-conglomerate, rudely alternating, and dipping 

 outwardly on all sides away from the central vent, at the same talus- 

 like angle of inclination as the most recent beds that have been seen 

 to flow down or fall upon the outer slopes, can we entertain any 

 doubts as to the mode of production of the entire mountains ? (See 

 fig. 9.) Or is it consistent with sound philosophy to hunt about for 

 some other and extraordinary hypothesis to account for it ? 



Consolidation of Lava on Steep Slopes. — The only argument of any 

 seeming weight that has been adduced by the upheavalists in sup- 

 port of their original views, is based on the assertion of M. Ehe de 

 Beaumont, as the result of his observations on Etna and elsewhere, 

 that no lava- current can, or has been ever seen to, consolidate upon 

 a slope having an inclination of more than 3° or at most 5°, and that 

 all lavas which have flowed down declivities exceeding this angle have 

 left no other traces than mere narrow and thin strips or a few loose 

 scoriform cakes upon such slopes. It is, in fact, upon this assertion 

 of M. de Beaumont that de Buch, Humboldt, and Dufrenoy pro- 

 fessed to rest their opinion that all volcanic cones containing beds of 

 solid lava dipping at angles of from 5° to 35° must have been 

 upheaved since the flowing of such lavas. 



So far as Etna is concerned, I leave this misrepresentation of 

 the fact to be dealt with by Sir Charles Lyell, who, in the elaborate 

 paper lately read by him before the Royal Society, and which will 

 shortly appear in the ' Philosophical Transactions,' has amply refuted 

 it from his own recent obsei'vations. But I may assert with con- 

 fidence that this pretended law as to the consolidation of lavas is 

 directly at variance with the commonest facts observable in perhaps 

 all volcanic districts. I have already alluded to the lava-streams which 

 I myself saw harden (and over which I frequently walked), on the 

 slopes of Vesuvius, at an angle of 33°, in the years 1819-22*. 

 Among the Buys of Central France many of the most recent lava- 

 streams, such as those of Nugere, Graveneire, and Pariou in Au- 

 vergne, that of the Mont Denise and others near Le Puy, several also 

 in the Yivarais, have congealed in bulky masses at angles of from 

 10° to 30°, both upon the outer slopes of the contemporaneous erup- 

 tion-cones, and in portions of their headlong course down some of 

 the steep river- channels which they have occupied — places in which 

 any notion of upheaval is out of the question. A recent visit in the 

 past summer to these localities enables me to make this assertion with 



* And many similar examples are at this moment to be obserred in the streams 

 produced from the same volcano by the eruptions of the last five or six years. 

 (See Roth, Vesuv. 1858.) 



VOL. XV. PAET I. 2 P 



