Page:Popular Science Monthly Volume 17.djvu/554

538 ones of lava, others of flint or obsidian. They were acquainted with gold and probably with copper, but those metals were rare with them. Woods were abundant, although there now exists only a single tree, a kind of palm, in all the archipelago. The vine, which is now cultivated almost exclusively, seems to have been unknown at that period.

The islands of Théra, Thérasia, and Aspronisi are the remains of a large island which existed before the formation of the bay. Their soil is composed of three classes of rocks: metamorphic rocks (marbles and mica-schists), volcanic rocks of subaërial formation, and volcanic rocks of submarine formation. Volcanic products of subaërial formation are the only ones in view in the larger part of the group. They appear as compact lavas, scoriæ, pumice, and in dikes. Fragments of the rocks in the dikes have been subjected to examination like that which was given to the lavas of the recent eruption, and the study has been applied to the solution of the problem of the specification of the triclinic feldspars. By it M. Fouqué has been led to conclude that the four varieties so described are distinct.

M. Fouqué accounts for the origin of Santorin by supposing that there was an island composed of marbles and mica-schists, against which submarine eruptions took place; a considerable upheaval then occurred. The eruptions having become subaërial, masses of matter were thrown out from different vents, and produced a large island, the slopes of which became wooded and its valleys fertile, while its summits continued to be rugged with lavas. A violent convulsion, accompanied and followed by formidable explosions and showers of pumice, hollowed out the bay. Finally, eruptions which have taken place since the beginning of the historical period have produced the Kamenis.

The phenomena of this volcano, which is one of those that were cited by Leopold von Buch, the principal advocate of the theory, as examples of the mode of formation which he suggested, have been carefully studied in view of their bearing upon the theory of craters of elevation. They appear, in the light of M. Fouqué's investigations, to contradict this theory at every point, to sustain the old arguments which have been brought against it, and to offer other features which are irreconcilable with it; so that the conclusion is reached that the theory must be definitively abandoned.—Revue Scientifique.