The Meteora is a rock formation in central Greece hosting one of the largest and most precipitously built complexes of Eastern Orthodox monasteries, second in importance only to Mount Athos. The six monasteries are built on immense natural pillars and hill-like rounded boulders that dominate the local area. It is located near the town of Kalambaka at the northwestern edge of the Plain of Thessaly near the Pineios river and Pindus Mountains.
Beside the Pindos Mountains, in the western region of Thessaly, these unique and enormous columns of rock rise precipitously from the ground. But their unusual form is not easy to explain geologically. They are not volcanic plugs of hard igneous rock typical elsewhere, but the rocks are composed of a mixture of sandstone and conglomerate.
The conglomerate was formed of deposits of stone, sand and mud from streams flowing into a delta at the edge of a lake, over millions of years. About 60 million years ago during the Paleogene period a series of earth movements pushed the seabed upwards, creating a high plateau and causing many vertical fault lines in the thick layer of sandstone. The huge rock pillars were then formed by weathering by water, wind and extremes of temperature on the vertical faults. It is unusual that this conglomerate formation and type of weathering are confined to a relatively localised area within the surrounding mountain formation.
This type of rock formation and weathering process has happened in many other places locally and throughout the world, but what makes Meteora’s appearance special is firstly the uniformity of the sedimentary rock constituents deposited over millions of years leaving few signs of vertical layering, and secondly the localised abrupt vertical weathering.