The geology of Greece is highly structurally complex due to its position at the junction between the European and African tectonic plates.
The Rhodope Massif spans the northern mainland, divided into amphibolite schist and gneiss, with comparatively recent granite intrusions from the Oligocene and Miocene.
West of the Strymonas River is the Serbo-Macedonian Massif, covering the Chalkidiki Peninsula with thick marble and gneiss, with granite intrusions.
[2] Additionally, the Olonos-Pindus Zone extends from Montenegro to Rhodes and is a deep allochthon trough, with clastic Triassic sandstone and the Drymos Limestone.
As the molasse basins filled during Burdigalian and Langhian times, the uplift of the Pindus Cordillera caused nappe formations to slide onto metamorphic rocks of the Cyclades.
Inland basins preserved numerous mammal fossils such as the Pikermi site north of Athens in continental clay.
Interior basins hold thick lakebed sediments from the Quaternary, indicating oscillation between cold desert conditions and wet interglacials.