GEOLOGY OF BOTTOM OF SEAS—DE LAUNAY. 349 
The ancients attributed the birth of all the islands in the 
Archipelago to a sudden upheaval in which the gods intervened, and 
likewise they thought that the islands could be engulfed by the 
anger of Poseidon. Although the origin of most of the large islands 
may have been entirely different, the ancients were not so far wrong 
as to their own region, for the history of Santorin, and of the 
famous island of Julia, are classic examples of like phenomena. The 
island of Julia appeared in 1831 between Sicily and Pantellaria. 
There were first some shocks; then, 15 days after, a column of 
water and smoke rose 25 meters high; a little later there was a 
column of 500 meters; finally there appeared an isle 4 meters high in 
the form of a crater, while the sea around was covered with dead 
fishes. In 5 days it rose from 4 meters to 20 meters, and a month 
after the first movement the island attained 1,600 meters in diameter. 
Six months later it was engulfed. It reappeared in 1863 to be 
swallowed up again. There were similar phenomena seen at Santorin 
in 1866, at the Azores, near San Miguel Island, in the Tonga Archi- 
pelago, and elsewhere. Saint Paul Island is a known example of 
an extinet volcanic crater which rises from the sea and which the 
sea invades. 
In other cases, submarine cables have been found with the gutta- 
percha covering completely melted. 
Marine movements of internal origin are of two kinds.1. There are 
first of all earthquakes properly so called, as their center of action may 
be on land orsea. Their principal effect as to land is the propagation 
of a vibratory wave, but with a regularity and a uniformity main- 
taining a mean, which are lacking on our continents. When a vessel 
is subjected to these earthquakes at sea there is the impression of its 
touching the bottom, without, however, suffering damage, and there 
is astonishment at not seeing the ocean foam on the reefs. Reaching 
the shore, the undulation produces tidal waves which may have been 
evident on the coast of Cornwall and on that of Brittany, but which 
are transformed into cataclysms on the shores of Japan and Sumatra, 
some of which, called tsunamis, have caused the death of 30,000 to 
200,000 persons. Other phenomena of volcanic origin have for their 
principal manifestation a projection of water to a great height, like 
that produced by a submarine explosion. Elevations of temperature 
are likewise observed in the deep beds, and sometimes fish seem thrown 
out like flying fish and cover the sea with their bodies. The region 
noted by Daussy, in the middle of the Atlantic, at the equator, is a 
well-known center for these phenomena. 
1 See Montessus de Ballore, La Science sismologique, p. 182 et seq. 
2 See 1838, Daussy: Note sur l’existence probable d’un volcan sous-marin (C. R. Ac. Sce., t. 6, p. 512).—. 
1858, Muller: Report on the facts and theory of earthquake phenomena (Rep. Brit. Ass., p. 20 et seq.; 
with chart representing the zone of Daussy). — 1887 to 1897, Rudolph: Ueber Marine Erdbeben und 
_ Eruptionen (Beitr. z. Geoph. her. von Gerland, 1887 pp. 133-165; 1894, pp. 537-666; 1897, pp. 273-336). 
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