VOLCANIC INFLUENCES. 43 



have stood on this old inland reef during the after- 

 noon, when the reflection of the sun's rays from the 

 surface of the present immersed bed of coral, in 

 front of Tajourah, has plainly showed the parallel- 

 ism of its outer edge with that of the reef upon 

 which I was standing, and a separation or indenture 

 in the latter also corresponded exactly with the 

 narrow channel in which anchorage is now found 

 near to the present shore, and which must have been 

 produced, in both cases, by the operation of similar 

 natural causes, acting under exactly similar circum- 

 stances. More alteration in this part of the world 

 has been produced by volcanic action than can be 

 conceived by endeavouring to form an idea of it by 

 comparison with the changes effected by the occa- 

 sional outbreaks of Vesuvius or Etna. Con- 

 vulsions of the earth, and ejection of molten lava 

 upon a most extensive scale, can only account for 

 the great alteration which has evidently, in modern 

 times, taken place in the physical geography of the 

 whole country of Arabia, the eastern shore of 

 Africa, and probably over a considerable portion of 

 the bed of the Indian Ocean in this neighbourhood. 

 Sir G. M'Kenzie's description of the phenomena 

 which have attended volcanic action in Iceland, 

 approaches somewhat to that which may be supposed 

 was here once exhibited, or that a succession of con- 

 vulsions, similar to the great earthquake of Kutch, 

 in Scinde, of which Sir S. Raffles gives such an inter- 

 esting account, have here, at some former period, 



