The overall landscape between Helike and Psathopirgos indicate a SE-NW trending tilted plateau. To the east, it is subsident and covered by the Selinous and Vouraikos fan deltas. To the west, it is uplifted and deeply incised by the Meganitas and Phoenix rivers. This plateau consists of a tilted basement of Mesozoic limestones, over which several hundred meters of mainly lacustrine sandy marls and conglomerates of middle Pleistocene age have piled mainly when the western Helike-Sella fault was active. This series is now uplifting due to the lock of that part of the fault and to the initiation of the Psathopyrgos-Selianitika-Aigion fault system.
Remnants of uplifted marine littoral terraces formed during transgressive middle and upper pleistocene high sea-levels are locally preserved along the Aigion block. Above Koumaries, U/Th dating of Pecten jacobeus (?) shells (age) suggest a terrace of MIS 9, and above Ziria village the occurrence of Spondylus gaederopus in a widespread platform indicates the warm Tyrrhenian terrace (MIS 5.5). Curves of the altitudes of the paleoshorelines along the NW-SE strike of Aigion block have been drawn along 7.5 km. Despite of small discrepancies likely due to minor faults observed in Aigion and west of the town, these curves confirm the tilting of the block and allow to precise its rate, ). using these chronological basis.
Stage 7.3 (216ka) : tiltrate : 1.45° ± 0 .1/100ka.
Stage 7.1 (194ka) : 1.45°/100ka
Stage 5.5 (125ka) : 1.36°/100ka
Stage 5.1 (80ka) : 1.43