Ixxii NOTES. 



( 306 ) p. 223. Kosmos, Bd. i. S. 244 (English edition, p. 223). 



(306) p. 223. Strabo, i. p. 58. Casaub. The epithet Sidirvpos shows that 

 mud-volcanoes are not here spoken of. Where Plato alludes to such in his 

 geognostical imaginations, in which he blends the mythical with the observed, 

 he says distinctly (in opposition to the phenomenon which Strabo has described) 

 vypov TnjAoD irorafMol. I have already treated, on another occasion (Bd. i. 

 S. 450452, Anm. 95; English edition, Note 225), of the expressions ir-r]\6s 

 and /5uo as applied to volcanic outpourings. I will, therefore, only recall here 

 another passage in Strabo (vi. p. 269), in which the hardening lava, termed 

 Tr-r)\bs jUe'Aas, is most clearly characterised. In the description of Etna it is 

 said : " The glowing current (^a|) in hardening petrifies the surface of the 

 earth to a considerable depth, so that he who would uncover it must undertake 

 the labour of a quarryman. For as in the crater the rock is molten, and then 

 uplifted, so the fluid which streams from the summit is a black mass of mud 

 (7T7?A.(fc) which flows down the mountain, and after hardening becomes fit for 

 mill-stones, and retains the colour which it had before." 



( 307 ) p. 224. Kosmos, Bd. i. S. 452, Anm. 98 (English edition, Note 

 228). 



( 30S ) p. 224. Leop. von Buch, Ueber basaltische Inseln und Erhebungs- 

 krater, in the Abhandl. der ion. Akademie der Wiss. zu Berlin, for 1818 and 

 1819, S. 51 ; and the same author's Physicalische Beschreibung der Canarischen 

 Inseln, 1825, S. 213, 262, 284, 313, 323, and 341. This work, which makes 

 an epoch in the well-based knowledge of volcanic phenomena, is the fruit of a 

 visit to Madeira and TenerifFe, from the beginning of April to the end of October, 

 1815. Naumann, however, notices very properly, in his Lehrbuch der Geogno- 

 sie, that in Von Buch's letters written from Auvergne in 1802 (Geognostische 

 Beob. auf Eeisen durch Deutschland und Italien, Bd. ii. S. 282), on the occasion of 

 the description of the Mont d'Or, the theory of elevation- craters, and their essen- 

 tial differences from volcanoes proper, were distinctly enounced. An instructive 

 companion-picture to the three craters of elevation in the Canaries (in the 

 islands of Palma, TenerifFe, and the Great Canary), is presented by the Azores. 

 The excellent maps of Captain Vidal, for the publication of which we are in- 

 debted to the British Admiralty, illustrate the wonderful geological conformation 

 of thos^ islands. In St. Michael we have the enormous Caldeira das sete 

 Cidades, formed almost under the eyes of Cabral in 1444, which is an elevation- 

 crater containing two lakes, the Lagoa Grande, and the Lagoa Azul, at a height 

 of 866 feet. The circumference of the Caldeira de Corvo, the dry portion of 

 whose floor is 1279 feet high, is almost as great. The elevation- craters of 

 Fayal and Terceira are situated at almost three times this height. To the same 



