PEINCIPLES 



OF 



G 



L 



G Y 



■>:^< 



BOOK II- — continued. 



CHAPTEE XXYI. 



ET:NrA. 



EXTEEXAL PHYSIOGXOMY OF ETNA — LATERAL CONES — THEIR SUCCESSIVE OBLI- 

 TERATIOX MARINE STRATA AT BASE OF ETNA OF NEWER PLIOCENE DATE 



OLDEST VOLCANIC ROCKS OF SAME DATE — FOSSIL PLANTS OF LIVING SPECIES IN 



ANCIENT TUFFS OF ETNA VAL DEL BOVE ON THE EASTERN FLANK OF ETNA 



INTERNAL STRUCTURE OF THE MOUNTAIN AND PROOFS OF A DOUBLE AXIS OF 



ERUPTION "S^'ANT OF PARALLELISM IN THE ANCIENT LAVAS DIKES IN THE 



VAL DEL BOVE, THEIR FORM AND COMPOSITION — TRUNCATION OF THE GREAT 



-ERUPTIONS OF ETNA OF HISTORICAL DATE ERUPTION OF MONTI ROSSI, 



-SCENERY OF THE VAL DEL BOVE ERUPTIONS OF 1811 AND 1819 — THAT 



OF 1852 — CHANGES WHICH IT HAS EFFECTED IN THE VAL DEL BOVE- 



CONE 

 1669 



-CASCADES 



OF LAVA IN THE VAL DI CALANNA 



-INCLINED LAVA OF CAVA GRANDE — FLOOD 

 PRODUCED BY THE MELTING OF ICE IN 1755— GLACIER PRESERVED BY A 



COVERING OF LAVA ANCIENT VALLEYS OF ETNA ANTIQUITY OF THE CONE OF 



ETNA. 



L 



External physiognomy of Etna. — Next to Vesuvius, our 



most authentic records relate to Etna, which rises near 

 the sea in solitary grandeur to the height of nearly 11,000 



feet.^ 



almost 



miles in circumference ; but if we include the whole district 



*■ In 1815, Captain Smyth ascertained, by careful barometrical measurement 



trigonometrically, that the height of 

 Etna was 10,874 feet. The Catanians, 

 disappointed that their mountain h ad lost 

 nearly 2,000 feet of the height assigned 

 to it by Eecupero, refused to acquiesce 

 in the decision. Afterwards, in 1824, 

 Sir J. Herschel, not being aware of 

 Captain Smyth's conclusions, determined 

 VOL. II, 



that the height was 10,872^ feet. This 

 singular agreement of results so differ- 

 ently obtained was spoken of by Herschel 

 as ^ a happy accident ; ' but Dr. Wol- 

 laston remarked that 'it was one of 

 those accidents which would not have 

 happened to two fools.' 



B 



