Methana volcano consists of a basaltic-andesite to rhyodacitic lava dome complex forming the Methana Peninsula in the Sarronian Gulf on the NE side of  Peloponnesus.  Potassium-Argon ages for the older part of the complex range from 900,000 to 550,000 years, although activity may have begun during the late Pliocene.  A younger phase of activity took place from about 380,000-290,000 years ago, forming a series of lava domes and flows.  The youngest dome, Kameno Vouno, on the NW side of the peninsula, was formed in the 3rd century BC and produced a lava flow that traveled 500 m beyond the coastline.  Hot springs are found at several locations along the coast of the peninsula.