The entire commune of "Aigrefeuille d'Aunis" is located on Jurassic sediments, which cover the entire plain of "Aunis" and extend into "Angoumois" north of the Charente river. Late Jurassic Limestone and marl outcrops appear clearly on the surface of the hilly part of the commune, while in the small depression which corresponds to the upstream part of the valley of Virson, are deposits from the Quaternary period. These are sedimentary deposits of fluvio-marine origin from the Flandrian transgression which were covered by further formations, specifically peat, due to congestion and stagnation of watercourses. There are many peat bogs east of the communal territory extending into the neighbouring commune of Forges.