Lake Servières in the Puy-de-Dôme department is a typical maar from a phreatomagmatic basalt eruption that dates back 8,000 years. This type of eruption occurs when rising magma meets surface water such as groundwater, streams, or lakes, causing violent explosions. The blast cuts circular craters called maars, which are bordered by pyroclastic crescents or rings and are sometimes filled by a lake or the sea over time. The Puy-de-Dôme department is home to numerous maars, especially in the Mont-Dore massif.