Geologically, the Greek area is divided into various geotectonic units and zones which present similar environments and age of formation. In general, the zones of Greece are divided into the External and Internal Hellenides zones. The Internal ones consist mainly of metamorphic rocks (from the Triassic, Jurassic, Mesozoic, Tertiary and Paleozoic) as well as igneous sediments (volcanic rocks, granites, etc.). The External ones consist mainly of sedimentary rocks, with the absence of metamorphic rocks. In the area of the Meteora-Pyli Geopark we encounter the following geotectonic zones – units:
- Mesohellenic Trough
- Koziakas – Western Thessaly Series
- Pindos Zone (Olonos-Pindos)
- Ophiolitic Nappe
- Pelagonian Zone
Figures 1 & 2 present the simplified geotectonic structure of the Geopark.
The origins of the Meteora-Pyli Geopark begin more than a billion years ago. The Antichasia area in the northern and eastern part of the Geopark is part of the Pelagonic zone, an old zone of Mesozoic rocks and Paleozoic metamorphic rocks. The Pelagonic zone was part of a large continent, Pangaea. The oldest rocks in the Geopark (and in the entire Greek area) are located near the village of Fotino, in the Antichasia area. Crystal analyses within the metamorphic and granitic rocks of the Pelagonian region have shown that they originate from older rocks that were part of the Amazonian craton (> 1 billion years old).
With the breakup of the Pangaea continent in the Triassic (~250 million years ago), large oceans and seas were created in which mainly deep-sea rocks were deposited (limestones, cherts, sandstones, etc.). These sediments also include some thick series of marine sediments (mudstones, conglomerates, sandstones, etc.), which are called Flysch. The largest ocean was known as the Tethys Ocean. Tethys was the daughter of Uranus and Gaia, wife of Oceanus, with whom she gave birth to three thousand river gods, among whom were Acheloos, Asopos and an equal number of female deities, the Oceanids. In the Tethys Ocean, the sediments that today constitute the Pindos, Gavrovo-Tripoli and the Koziakas ranges were deposited. East of these, on a mid-oceanic ridge, new oceanic crust was created by submarine volcanic activity, similar to that of the Atlantic ridge today. These volcanic rocks and their accompanying sediments today constitute the Ophiolitic nappe.
With the end of the Mesozoic, the Alpine orogen began, the last stage of mountain range formation in the Greek area. During the period 40-20 million years ago, the marine rocks were uplifted, compressed and moved westward. This tectonic deformation and movement led to the placement of the Pindus belt on the rocks of the Gavrovo-Tripoli belt, as well as the Koziaka Series and the ophiolites on Pindus. The impressive folds and faults on both small and large scales that we observe today in the rocks of Pindus and Koziaka are the result of these compressive forces.
During the Alpine orogeny, west of the Pelagonian, a new sea was created from the region of Albania to the region of Domokos. The Meso-Hellenic Trench as it is known (30-10 million years old) includes a large series of sedimentary rocks, mainly sandstones, clays, conglomerates and marls. The rocks of Meteora consist of the Meteora Conglomerates, a series of cohesive conglomerates and sandstone beds, part of the Pentalofos-Meteora Formation of Upper Oligocene – Lower Miocene age (10-30 million years). The Meteora Conglomerates were deposited in a system of submarine river deltas, on the margins of the Meso-Hellenic Trench. Their material consists of pebbles of metamorphic rocks of the Pelagonian, which were transformed from the east by rivers and streams.
The geological structure is complemented by younger Quaternary formations (2.5 million years) of lateral clasts on the mountain slopes, clast cones, glacial moraines and other deposits, river terraces and modern river alluvium.
During the recent geological past (~ 5 million years to the present), the uplift of the Pindos and Mesohellenic mountain ranges stopped and today gradual erosion takes place through the creation of deep valleys and large landslides. The sediments of the Mesohellenic Trough are gradually eroding and have revealed the harder Meteora Conglomerates that dominate today over the Kalambaka and Antichasia areas. During the Pleistocene (2.5 million years) numerous glacial periods led to the formation of glaciers in the high Pindos mountains. Today there are no glacier remnants, but at altitudes above 1600 meters the morphology has been shaped by the glacial activity, creating glacial valleys and deposits (Lakmos, Triggia, Avgo, Marosa, Kakarditsa, Athamanika, etc.).
