Geology of the Bosphorus. 191 
crater of eruption, we must suppose that this crater is now 
hidden beneath the waters of the Black Sea, possibly at some 
little distance from the shore. It is certain that these volcanic 
rocks extend out under the sea, to some distance, and there 1s 
nothing in the nature of the case to make it improbable that 
there was once a vast volcano there, which vomited out all the 
eruptive rocks on both sides of the Bosphorus as far down as 
s. 
he only historical evidence upon the subject is the tradition 
of the Cyanean rocks or the Symplegades. There are certain 
the Bosphorus, about twenty stadia apart, one near the Euro- 
pean and one near the Asiatic shore. The rocks now called 
the main land within a short period of time. Their geological 
composition is exactly similar to the nearest point of the coast 
which is only fifty feet distant, and is connected with the island 
y a continuous ledge of rock, with deep water on either side, but 
e 
this passage through the rocks. If Strabo ever saw the islands 
of which he speaks, which is doubtful, they have since disap- 
sole either worn away by the sea or sunk beneath its waters. 
omer, in the Odyssey, says of these rocks: ‘These then are 
ofty rocks, and near them the vast wave of apoienie: re- 
ere 
destructive fire take away planks of ships and bodies of men 
together. Ake Argo a: ete. Heat passage, I think it 
se | be inferred that the Cyanean rocks were active volcanoes, 
and that at least the tradition of such voleanic islands was 
current in the time of Homer. What is said of the birds con- 
mms the idea, for it can hardly be imagined that birds could 
be caught by the islands coming together though they might 
by volcanic eruption. ; 
