. oi 
250 DYNAMICAL GEOLOGY. — [Book 
“3ne 
on the west coast of Iceland. An island was built up, from which fire 
and smoke continued to issue, but in less than a year the waves had 
-washed the loose pumice away, leaving a submerged reef from five 
to thirty fathoms below sea-level. Abouta month after this eruption 
the frightful outbreak of Skaptar Jokull already (p. 224) referred to 
began, the distance of this mountain from the submarine vent being 
nearly 200 miles... Again in the year 1831, a new volcanic island - 
(Graham’s Island, Ile Julia) was thrown up, with abundant discharge 
of steam and showers of scoriz, between Sicily and the coast of Africa. 
It reached an extreme height of 200 feet or more above the sea-level 
(800 feet above sea-bottom) with a circumference of 3 miles, but on 
the cessation of the eruptions was attacked by the waves and soon 
demolished, leaving only a shoal to mark its site.” In the year 1811 
another island was formed by submarine eruption off the coast of 
St. Michael’s in the Azores. Consisting, like the Mediterranean 























































































































































































































Pia. 57.—Skercu or Susmartwe Vorcanic Eruption (SaBrina IsLAND) OFF 
St. MicHAE.’s, June#, 1811. 
example, of loose cinders, it rose to a height of about 300 feet with a 
circumference of about a mile, but subsequently disappeared.? In 
the year 1796 the island of Johanna Bogoslawa in Alaska appeared 
above the water and in four years had grown into a large volcanic 
cone, the summit of which was 3,000 feet above sea-level.* 
Unfortunately, the phenomena of recent volcanic eruptions under 
' Lyell, Principles, ii. p. 49. 
* Phil. Trans. 1832. Constant Prevost, Ann. des Sci. Nat. xxiv. Mém. Soc. Geol. 
France, ii. p. 91. 
® De la Beche, Geol. Obs. p. 70. 
* D. Forbes, Geol. Mag. vii. p. 323, 

