Notice of Graham Island. 99 



hai-d under the feet. No variety of lava was procured, nor 

 even any jet or streams of lava seen ; and Mr. Osborne, sur- 

 geon to His Majesty's ship Ganges, states that the substances 

 of which the island is composed, are chiefly ashes, the pulver- 

 ized remains of coal deprived of its bitumen, iron scorioe, 

 and a kind of ferruginous clay, or oxided earth. The scorise 

 occur in irregular masses, some compact, dense and sonorous, 

 others light, friable, and amorphous, with metallic lustra, 

 slightly magnetic, barely moving the loadstone. A piece of 

 limestone was also found thrown up with the other substances, 

 having no marks of combustion. There were, according to 

 the same observer, no traces of lava, no terra puzzolana, no 

 pumice, nor other stones, usually found on volcanic hills. 



It will at once be observed, in the sketches of the island 

 which are represented by pi. iv., that its appearance differs 

 very much according to the distance at which it is viewed. 

 In Fig. 1, it is the summit of a volcano, a cone of eruption 

 slightly elevated above the level of the sea ; but, on a nearer 

 approach, its form is found to be that of a circular crater with 

 more or less perpendicular walls (Fig. 2.) like most of the 

 craters of elevation surrounding the internal craters of volca- 

 noes, or the islands and insulated formations of supposed simi- 

 lar origin. The internal crater on the left hand side of Fig. 

 2, which presents the most striking manifestation of this dis- 

 position, has been obliterated in the sketch contained in the 

 Journal of the Royal Geographical Society, and occupied by 

 smoke and a prodigious flash of lightning. 



There is every reason to believe that volcanic eruptions take 

 place at the bottom of the sea, in the same manner as on the 

 surface of a continent ; and Mr. Osborne points out the fact 

 that, in the elevated sides of the external ridge of the island, 

 the sides fall down in abrupt precipices ; and each stratum 

 could be distinctly discerned, the water evaporating having 

 left an incrustation of salt, which now appears a white firm 

 layer, plainly marking the regular progress and formation of 

 the island. It is very evident that this kind of action and 

 succession could not have taken place above the level of the 

 waters either of the sea or of the internal crater ; as it further 

 demonstrates that iiorizontal beds of volcanic matters, accumu- 

 lated over each other, can be directed on a given point without 

 any violent contortion or derangement of their symmetry and 

 parallelism. Nor have we, in the present case, any invasion 

 of the sea or explosions posterior to the formation of the cone, 

 if we may judge from the details transmitted to us of the ele- 

 vation and appearance of the island, to account for the well 



