This location is in the centre of the blueschist area in the north if Sifnos. These rocks are linked to the subduction (or diving under) of the African plate under the Peloponnese. At a depth of more than 50km, the rocks were heated up to temperatures of higher than 500 degrees celcius under a high pressure. This type of of heat-pressure combination leads to changing the crystalline structure of the rocks. Blueschists are such a type of metamorphic rocks.