The Chaîne des Puys is a group of volcanic hills, lava domes, and maars that stretch from north to south in the Massif Central region of France. This volcanic chain is about 40 kilometers (25 miles) long and includes 48 cinder cones, eight lava domes, and 15 maars and explosion craters. The highest point in the chain is the lava dome called Puy de Dôme, which stands at 1,465 meters (4,806 feet) and is located near the center of the chain. The name "Chaîne des Puys" comes from the French word "puy," which means a rounded volcanic hill. The last known eruption in the Chaîne des Puys area occurred around 4040 BC.

The Chaîne des Puys region shows how tectonic plates move and the Earth's crust splits apart. In 2018, this area was recognized as a UNESCO World Heritage Site.

Formation

The Chaîne des Puys is located on the Limagne fault, a major part of the European Cenozoic Rift System, which formed during the creation of the Alps about 35 million years ago. The area has many different types of geological features caused by the rifting. The mountain chain itself began to form about 95,000 years ago, and the volcanic activity that created the range stopped around 10,000 years ago. Most of the cones were formed by Strombolian eruptions, and these cones usually have clearly defined summit craters. Some cones have craters inside other craters, and others show broken edges where lava flowed out.

In contrast, Puy de Dôme was formed by a Peléan eruption. This type of eruption is known for long periods of inactivity that are sometimes interrupted by sudden, very powerful eruptions.

Future eruptions at the Chaîne des Puys could happen, and they might lead to the creation of new mountains.

Research

Before 1750, the Puys were believed to be man-made structures, such as piles of mining waste or Roman forge furnaces. The chain was studied in early research by English geologist George Julius Poulett Scrope, beginning in the 1820s. In 1827, he published his Memoir on the Geology of Central France, which included descriptions of volcanic formations in Auvergne, the Velay, and the Vivarais. This work was later revised and made more accessible in a 1858 book titled The Geology and Extinct Volcanoes of Central France. These publications were the first widely shared descriptions of the Chaîne des Puys. The research in these books helped establish important ideas that became the basis of volcanology.