Geological information - Sarakiniko - Glaronissia - Minerals - Fossils - Other photos
The island of Milos is almost entirely a volcanic island. Visitors, even without specialised knowledge, will surely be impressed by the images they see at every step which undoubtedly will be imprinted on their minds for ever or on photographic film.
The colours and morphology of the geological phenomena... the coastlines, the gulfs, the cliffs, the gorges, the hills... are unique and it would be difficult to tire of gazing at them.
Milos is said to belong to the pelagonic zone by the majority of those acquainted with the tectonic geology of Greece, although others would ascribe it to the pre-pelagonic zone.
In accordance with the theory of the lithospheric plate, it has been proved that Milos lies on the Eurasiatic Plate and 220 km. from the collision boundary with the African Plate. The latter is gradually moving under the former plate, at a speed of 2.5 cm. per year and at an angle of 35o to the horizontal. This movement is evident in Milos Island, especially in the south, where the land is slowly sliding down into the sea.
Using radio-active dating techniques, it has been estimated that volcanic activity in the Southern Aegean began 2-3 million years ago. In Milos, activity ceased 90,000 years ago, which is considered to be recent on a geological time scale. (Extinct volcanoes are to be seen at Firiplaka and Trachylas).
Eruptions took place on land and sea and as evidence of this, fossils of both land and sea organisms, can be found in the tufa (volcanic rock). Some examples of these are: pecten Jako-baeus, pinna pectinata, ostrea edulis and balanus.
Apart from these volcanic rock types, there are also examples of sedimentary rocks (Provatas, S. Milos) and metamorphic rocks. The former were believed to have been formed 14 million years ago and the latter 33 and 64 million years ago.
At this point, it is worth mentioning some geological features which are a direct result of the island's volcanic nature.
Firstly, the two extinct volcanoes; the one at Firiplaka, on the south coast, has an impressive and well-preserved crater, with a diameter of 1.700 metres and height of 220 metres approximately. The other is at Trachylas, NNW Milos, although only a small part of it remains.
Another geological formation is that of the steep-sided hills such as Castro, which rises above Plaka, and Prophet Elias. These volcanic «plugs» were formed when magma, from under the earth’s crust, failed to erupt, due to low gas pressure. This molten rock solidified inside the volcanic pipe to form a hard rock called andesite. Subsequently, the softer surrounding rock was worn away exposing the hard rock cylinder or «plug».
The «Seagull Islands», off the north coast, are a remarkable and rare example of andesite column formation. These islets are entirely made up of vertical, pentagonal and hexagonal prisms, 20-30 cm in diameter, in majestic array.
Also on the north coast is Sarakiniko where fossils of land and sea organisms abound. Here, layered variations of white volcanic rock interplay, to create a dramatic land and sea-scape. This, together with the total absence of vegetation, gives us the distinct impression that we are ...on the Moon.
Today there is still strong evidence that Milos lies on the southern Aegean volcanic arc. The old volcanoes may be extinct, but there are still numerous indications that the surface is directly influenced by the core of the earth.
One of the volcanic characteristics is the geysers, mostly in the east and south-east, where gases, mostly carbon dioxide, hydrogen sulphide and steam, issue through apertures in the rocks, often causing yellow colouration, the well-known sulphur smell and elevated surface temperature eg. Ag. Kyriaki 102o C, Pyromenes 100o, Paliochori 101o C, Vounalia 54o C, Kastanas 86o C, Adamas 100o C. At points where this occurs under the sea, bubbles of gas are visible on the surface and again the same characteristic smell and elevated temperature. Examples may be seen at Ag. Kyriaki, Paliochori, Kanava and Rivari.
There are also a number of hot springs, some of which are spas and although they have never been adequately exploited, Hippocratis mentions them in his writings«On Epidemics». We are told that Atheneans with dermatological problems went to the spas on Milos, in search of a cure.
These springs are at sea level in Adamas for example, where public baths have been built - the temperature reaching 33,3o C. Further examples are, Alikes (22o C), Kanava (50o C), Paliochori (50o C), Mandrakia (54o C), Adamas Haros (42o C), Provata and Tria Pigadia and elsewhere.
The chief salt present in the waters is sodium chloride, but the sulphates of calcium, magnesium, potassium and ammonia are also to be found, along with carbon dioxide and silicon dioxide. The spa waters are considered to remedy rheumatoid arthritis, gynaecological and dermatological illnesses among others. These areas also exhibit elevated land temperatures.
Over millions of years, these high surface temperatures have resulted in the formation of rich mineral deposits, which are now extensively mined. Furthermore, after long term research involving extensive drilling, by the D.E.H. (Public Electricity Service) and the I.G.M.E. (Institute of Geological Research), it was found that there is a geothermic field under the island with highly pressurised steam at an approximate depth of 1.100 metres. This could prove to be a valuable source of power, both electrical and otherwise, provided the technical problems can be overcome.