Santorini [Geography and Geology]

The present-day crescent shape of the island is a consequence of the activity of the volcano in prehistoric times. The island itself owes its very existence to the volcano. The limestone rocks of Prophitis Ilias, Gavrilos [Platynamos] and Monolithos initially comprised islets in this corner of the Aegean. Through this region, however, passes the line at which two large plates of the earth's crust meet: the African and the Aegean plate. Thus is explained the premature volcanic activity in this zone. The limestone islets were surrounded by lavas so that, slowly but surely, they were united, thus forming eventually one large island. Tradition refers to this island by the name of Strongyle [Round] which probably derives from its shape. At the beginning of the final phase of human prehistory in the eastern basin of the Mediterranean, that is in about 1500 B.C., an immense eruption of the volcano shattered Strongyle completely. Its central section was submerged into the depths of the sea which rushed into the void that had been created. What remained after this blasting to smithereens are the present-day islands of Santorini, Therasia and Aspronisi. The volcano, however, did not become extinct. From time to time it awoke bringing lavas to the surface from the very bowels of the earth. So, in time, the two islets in the centre of the caldera were created, that is in the sector filled by the sea after the prehistoric sinking. These islets are Palea Kameni --Hiera [Holy isle] of the ancient Greeks, which was born in 197 B.C. --and Nea Kameni, a later creation following successive eruptions of the volcano. On Nea Kameni is the crater from which, even today, gases and steam at a temperature of 80ÁC are emitted.

The walls of the caldera constitute a unique section through the earth for study by specialist geologists and vulcanologists. It is a veritable museum of all the lavas the volcano has produced during each phase of its activity. The surface layer, the top of which comprises the present-day soil of Santorini, is enormous quantities of pozzuolana and pumice. This layer is preserved in the low-lying plains of the island and hollows in the ground for it has been displaced from the hill tops due to millennia of erosion. For this reason it varies in thickness from 0 to 40 metres. Until very recently, prior to the influx of tourism, this layer furnished the basis of the islandÍs economy. The quantities of pozzuolana and pumice which are exported annually from Santorini are estimated at 2 million tons.

Its volcanic origin has made the soil of Santorini extremely fertile and favourable to all types of cultivation. If it were not for the shortage of water the island would be a perpetually verdant garden since it is blessed with an excellent climate. Cultivation, however, is limited to early vegetables --tomatoes, fava [split-pea], petit-pois --and cereals, mainly barley. The [p. 10] only perennial crop propagated is the vine. Its wines are renowned for their quality and variety.

[Doumas, Christos, Prof. of Archaeology at the Univ. of Athens, Director of Excavations at Akrotiri. Santorini, A Guide to the Island and Its Archaeological Treasures. Athens: Ekdotike Athenon S.A. 1995.]