Note 382 — GEOLOGICAL ILLUSTRATIONS, (continued 2)

A remarkable fact of this kind is related by Salt, in his second journey to Abyssinia. The Bay of Amphila, in the Red Sea, is formed, he says, of twelve islands, eleven of which are in part composed of alluvial matters, consisting of corallines, madrepores, echinites, and a great variety of shells common in that sea. The height of these islands is sometimes thirty feet above high water. The small island, which differs from the eleven others, is composed of a solid limestone rock, in which veins of calcedony are observed. Does not this small island, we may ask, indicate that some cause has prevented the madrepores from covering it, while they constructed their habitations in the neighbourhood, on bases which probably must be of the same nature as those of the small island?