Megalopolis Lignite Mines

The Megalopolis lignite mines are a group of open-pit coal mines in the Megalopolis Basin of the central Peloponnese, southern Greece, operated by the Greek Public Power Corporation (PPC S.A.) since 1969 and among the largest coal mining districts in the country.¹ The basin holds initial mineable lignite reserves of about 434 Mt, and its deposits have supplied two power plants with a total installed capacity of 850 MW, fed annually with roughly 12 Mt of lignite.¹

Geology and the lignite–detritus cycles

The Megalopolis Basin is an intermontane basin near the center of the Peloponnese Peninsula (37°25′N, 22°10′E, 400 m above sea level), formed by extensional tectonics with active subsidence and deposition during the Pliocene and Pleistocene.⁵ Its sedimentary fill includes the Marathousa Member of the Choremi Formation, composed of lacustrine clay, silt, and sand beds alternating with lignite seams; these deposits represent a large lake that periodically became a shallow swamp.⁶ The drilled lignite-bearing Marathousa Member reaches a thickness of up to about 200 m in the center of the basin.⁷

The alternation of lithologies records climate cycles. Detrital beds most likely formed during cold, dry periods and correlate with glacials or stadials, while the lignite beds represent interglacials or interstadials, formed under warm and humid conditions.⁶ A palynological study of the Marathousa Member argued that these lignite–detritus lithological cycles have an astronomical (orbital) origin, comprising a first-order alternation of lignites and detrital muds and a second-order alternation expressed by frequent intercalation of organic layers.⁵

Magnetostratigraphy anchors the sequence in time. A magnetic polarity reversal observed within a roughly 10 m-thick lignite seam at the base of the exposed stratigraphic sequence was interpreted as the Brunhes/Matuyama boundary at 0.78 Ma, consistent with the boundary falling within warm Marine Isotope Stage 19.⁸

Mining history and production

The first survey of the Megalopolis lignite deposits was conducted in 1957, and exploitation of the deposit began in 1970; it was the first time worldwide that lignite of such low quality was mined and used for electricity generation.³ The lignite field is divided into four major basins: Kyparissia, Thoknia, Marathousa, and Choremi.²

Annual production rose gradually from 4.1 Mt in 1971 to 14.5 Mt in 2002, the maximum, and was maintained at 13–14 Mt per year until 2008, when a gradual decline began. In the five-year period 2015–2019 production ranged from 6 to 8 Mt per year, and in 2020 the Megalopolis mines produced 2.8 Mt.³ PPC planned that the production operation of the Megalopolis mines would be discontinued by the end of 2023, as part of a rapid lignite phase-out.³ By the mid-2020s only the Choremi lignite mine was still operating, and with two lignite power units ceasing operations in 2020 and the remaining units nearing cessation, the region faces a transition from a mining-centric economy to post-mining rehabilitation.²

Mining reshaped the landscape. The Alfeios River was rerouted in 2002 into a 7 km long channel along the western side of the lignite mine, and continuous pumping and diversions failed to fully mitigate water inflows, leading to pit lakes that merged into a larger lake in 2012.^{9 • 2} Reclamation plans include a pit lake at the Choremi mine, agricultural and livestock lands, timber production, an industrial park at the external deposits of the Marathousa mine, protection of the archaeological sites, and two photovoltaic projects.¹⁰

Coal quality

The Seam I lignite in the Marathousa Mine is a very low-rank coal with high mineral matter and sulfur contents, and its natural radionuclide concentrations are higher than those of typical coals worldwide.¹ Very high pyrite and uranium contents, features usually suggesting marine influence during deposition, are instead attributed to a karstic aquifer that supplied the palaeomire with sulfate-rich, neutral to weakly alkaline water, with pyrite formation and uranium precipitation occurring under the anaerobic conditions that prevailed during peat accumulation.¹ Radiochemical constituents are released to the atmosphere during combustion as fine fly-ash particles, while an important amount remains in the bottom ash.¹

Archaeological discoveries in the mines

Because opencast mining strips back the overburden, the mines have exposed thick sequences of fossiliferous Middle Pleistocene deposits, and numerous palaeontological localities have been exposed during mining operations since 1969.⁶ The best documented is Marathousa 1, discovered in 2013 during a targeted palaeoanthropological survey inside the open-cast mine and excavated by an interdisciplinary team from the Ephoreia of Palaeoanthropology–Speleology of Greece and the University of Tübingen.⁴ Systematic excavations exposed 72 m² and revealed a partial skeleton of the straight-tusked elephant Palaeoloxodon antiquus in spatial and stratigraphic association with a small-tool lithic assemblage, with cut marks and percussion damage indicating butchering; hominin activity at the site occurred between about 0.5 and 0.4 Ma, within Marine Isotope Stage 12.^{4 • 8} Marathousa 1, approximately 430,000 years old, which stands as the Southern Balkans' sole Lower Palaeolithic butchering site, is no longer the oldest archaeological site known in Greece, that distinction belonging to Kyparissia 4, dated to approximately 700,000 years ago.^{4 • 14}

A five-year field and geoarchaeological survey in the lignite mines reported in 2023 identified five newly discovered localities spanning roughly 700,000 to 280,000 years ago, including Kyparissia 4 (about 700,000 years old, with stone artifacts and remains of giant deer, hippopotamus, rhinoceros, elephant, and a macaque tooth), Marathousa 2 (about 450,000 years old, with a hippopotamus skeleton bearing cut marks), Tripotamos 4 (about 400,000 years old, with a large concentration of stone tools), and Choremi 7 (about 280,000 years old, with processed deer bones). These finds suggest that Megalopolis constituted one of the southernmost ecological shelters of Europe during the Ice Age.¹¹ Marathousa 2, situated just below Lignite Seam III, provides one of the few examples of hippopotamus carcass processing during the Lower Paleolithic in Europe.¹²

Mining has also damaged the archaeological record: Marathousa 1 lies on the edge of a lignite mine, and while the total extent of the site remains unknown, a significant portion may have been destroyed by mining operations.¹³

References

1. Siavalis, G., Linou, M., Chatziapostolou, A., Kalaitzidis, S., Papaefthymiou, H., Christanis, K. (2009). Palaeoenvironment of Seam I in the Marathousa Lignite Mine, Megalopolis Basin (Southern Greece). International Journal of Coal Geology 78(4), 233–248.
2. A comparative analysis of semi-quantitative multi-hazard methodologies with an application to a post-mining area. Natural Hazards (2025).
3. Conventional Generation, PPC Group.
4. Panagopoulou, E., Tourloukis, V., Thompson, N., Konidaris, G., Athanassiou, A., Giusti, D., Tsartsidou, G., Karkanas, P., Harvati, K. (2018). The Lower Palaeolithic site of Marathousa 1, Megalopolis, Greece: Overview of the evidence. Quaternary International 497, 33–46.
5. Okuda, M., van Vugt, N., Nakagawa, T., Ikeya, M., Hayashida, A., Yasuda, Y., Setoguchi, T. (2002). Palynological evidence for the astronomical origin of lignite–detritus sequence in the Middle Pleistocene Marathousa Member, Megalopolis, SW Greece. Earth and Planetary Science Letters 201(1), 143–157.
6. Marathousa 1: a new Middle Pleistocene archaeological site from Greece. Antiquity Project Gallery.
7. Bludau, I. J. E., et al. (2026). Drilling the Marathousa palaeo-lake in Greece (Peloponnese): inferring the environmental context of a Middle Pleistocene archaeological site. Boreas 55(3), 866–884.
8. Magnetostratigraphic and chronostratigraphic constraints on the Marathousa 1 Lower Palaeolithic site and the Middle Pleistocene deposits of the Megalopolis basin, Greece. Quaternary International 497, 154–169 (2018).
9. Lake-Level Changes and Their Paleo-Climatic Implications at the MIS12 Lower Paleolithic (Middle Pleistocene) Site Marathousa 1, Greece. Frontiers in Earth Science (2021).
10. WINTER Project: Best Available Techniques guide for land rehabilitation and reclamation (2021).
11. Mouratidis, G. Megalopolis – lignite mines of Megalopolis – 2023. Chronique des fouilles en ligne, notice 18541.
12. Konidaris, G., et al. (2023). Marathousa 2: A New Middle Pleistocene Locality in the Megalopolis Basin (Greece) With Evidence of Hominin Exploitation of Megafauna (Hippopotamus). PaleoAnthropology 2023(1).
13. De Caro, D., Kuhn, M., Thompson, N., Panagopoulou, E., Harvati, K., Tourloukis, V. (2025). Small flakes for sharp needs: Technological behaviour in the Lower Palaeolithic site of Marathousa 1, Greece. PLoS One 20(6): e0324958.
14. Greek archaeology started a quarter of a million years earlier than thought: 700.000 years old site found, University of Tübingen

Topic: Encyclopedia › Technology and the built world › Energy technology › Coal industry and mining › Coal mines of Europe

Initially written Oct 20, 2026

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