History of the Peloponnesian War

Opposite to Oeniadae lie most of the islands called Echinades, so close to the mouths of the Achelous that that powerful stream is constantly forming deposits against them, and has already joined some of the islands to the continent, and seems likely in no long while to do the same with the rest.

For the current is strong, deep, and turbid, and the islands are so thick together that they serve to imprison the alluvial deposit and prevent its dispersing, lying, as they do, not in one line, but irregularly, so as to leave no direct passage for the water into the open sea.