The Chaîne des Puys is a north-south oriented chain of cinder cones, lava domes, and maars in the Massif Central of France. The chain is about 40 km (25 mi) long, and the identified volcanic features, which constitute a volcanic field, include 48 cinder cones, eight lava domes, and 15 maars and explosion craters. Its highest point is the lava dome of Puy de Dôme, located near the middle of the chain, which is 1,465 m (4,806 ft) high. The name of the range comes from a French term, puy, which refers to a volcanic mountain with a rounded profile. A date of 4040 BC is usually given for the last eruption of a Chaîne des Puys volcano.
View of the Chaîne des Puys from Puy de Dôme
In volcanology, a lava dome is a circular, mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on Earth form lava domes. The geochemistry of lava domes can vary from basalt to rhyolite although the majority are of intermediate composition The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite.
Rhyolitic lava dome of Chaitén Volcano during its 2008–2010 eruption
One of the Inyo Craters, an example of a rhyolite dome
Nea Kameni seen from Thera, Santorini
Lava domes in the crater of Mount St. Helens