128 



Prof. J. Prestwich. 



independence of the causes leading to the outflow of lava, and those 

 generating the elastic vapours, is that of Santorin in 1866, .recorded 

 by M. Fouque.* In the centre of the bay formed by the great 

 encircling old crater-walls of the islands of Thera and Asprosini, 

 stands the small island of Kaimeni, the product of later eruptions. On 

 the 26th January, 1866, the loose blocks on the southern slope of this 

 island began to move — on the 27th slight shocks were felt, gases 

 evolved, and fissures rent in adjacent buildings. The ground in a 

 small sandy bay Was observed to rise, and by the 4th February the 

 erupted mass consisting of blocks of lava, had attained a height of 

 32 feet. By the 5th, this protuberant mass of lava had increased to 

 230 feet in length by 98 feet in width, and 65 feet in height, and on 

 the 7th to 492' x 197' X 98'. The adjacent water was hot and the 

 surface of the lava was consolidated, though it was incandescent at 

 night. Until the 12th February there were no detonations and no 

 explosion, notwithstanding the large quantity of lava emitted, for it 

 was not confined to the matter above water, but it was, in places, 

 gradually filling up the bay itself ; and where there previously had 

 been soundings of 103 fathoms, the depth was now reduced to from 

 40 to 70 fathoms.f 



M. Fouque remarks, J that " at the beginning of the eruption the 

 discharge of lava was the most salient phenomenon ; the rock- emission 

 proceeded in silence ; it was only at the end of several days that the 

 explosions and ejections commenced and a crater formed (the volcano 

 of Giorgios)." The explosions attained great violence On the 20th and 

 22nd, and on the latter day the column of vapour and ashes rose to a 

 height of about 7000 feet. In April and May lava flowed more freely. 

 The eruption was prolonged to 1869, when the explosions were still 

 frequent hut the discharge of lava very small. 



Another eruption commenced in February 1867, in the sea-bed west 

 of Kaimeni, and by the 17th an island (Aphroessa) was formed 

 328 feet long by 196 feet wide and 32 feet high ; while the adjacent 

 sea-bed was in places reduced from a depth of 296 fathoms to 

 108 fathoms. This also was effected quietly and without noise, and it 

 was not until later that the explosions began. 



So noiseless and so steadily continuous was the protrusion of these 

 masses of lava at first, that Dr. Cigalli, who watched them from day 

 to day, compared their growth to the steady and uninterrupted growth 

 of a soap bubble. 



Much of the lava of this great eruption was very compact, and not 

 at all scoriaceous.§ 



* " Santorin et ses Eruptions," Paris, 1879. 

 f Ibid., p. 36 et seq. 

 X Ibid., p. xv. 

 § Op. ext., p. 72. 



