230 REACTION OP THE INTERIOR OF THE EARTH 



appearance of the Mexican volcano with the volcanic elevation 

 of the Hill of Methone, now Methana, in the peninsula of 

 Trcezena, a phaenornenon of which the description by Strabo 

 and Pausanias led one of the Roman poets endowed with the 

 richest fancy to develop views strikingly accordant with those 

 of modern geology. " Near Troezena is a tumulus, steep and 

 treeless, once a plain, now a mount. The vapours, pent up in 

 dark caverns, in vain sought an outlet ; thus constrained, 

 their powerful force caused the inflated ground to swell up- 

 wards, like a bladder or goat-skin filled with air. The 

 ground thus raised still remains, but has been changed 

 by time into a hard rock/' ( 23 ) Thus picturesquely, and, 

 as analogous phenomena justify us in believing, thus truly, 

 does Ovid describe the great natural phsenoinenon which 

 took place between Troezena and Epidaurus, 282 years 

 before our era ; 45 years therefore before the volcanic sepa- 

 ration of Thera (the island of Santorin) from Therasia. 

 In the same spot Eusseg'ger found intersecting veins of 

 trachyte. 



Of all " islands of eruption," belonging to volcanic chains, 

 Santorin is the most important as an object of study : "it 

 is a complete type of islands of elevation : for more than 

 2000 years, or as far back as history and tradition enable 

 us to trace, efforts of nature to form a volcano in the middle 

 of the crater of elevation seem to have been perpetually going 

 on/' ( 231 ) Near the island of St. Michael, in the Azores, 

 similar insular elevations manifest themselves at almost 

 regularly recurring intervals of eighty or ninety years ; ( 232 ) 

 but in this case the bottom of the sea is not always raised 

 at precisely the same points. The island to which Captain 

 Tillard gave the name of Sabrina, appeared at a time 

 (30th January, 1811) when unfortunately political events 



