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Mont Gerbier De Jonc
Mont Gerbier de Jonc is a mountain of volcanic origin located in the Massif Central in France. It is made of a type of rock called phonolite. It rises to an altitude of , and its base contains three springs that are the source of the Loire, France's longest river. It is the second most-visited site in the ''département'' of Ardèche, after the Ardèche Gorges. Mont Gerbier de Jonc was formed 8 million years ago when a volcano erupted molten phonolite lava. The lava was too viscous to flow far and it cooled to form a lava dome of phonolite rock in the crater of the volcano. The lava dome has columnar jointing, which formed during cooling of the lava. The volcanic cone containing the lava dome was later eroded Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust, and then sediment transport, tra ... away, exposing the lava ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ardèche
Ardèche (; oc, Ardecha; frp, Ardecha) is a department in the Auvergne-Rhône-Alpes region of Southeastern France. It is named after the river Ardèche and had a population of 328,278 as of 2019.Populations légales 2019: 07 Ardèche INSEE Its is in Privas, but its largest city is Annonay. History Prehistory and ancient history [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pacific and Indian Oceans. Its Metropolitan France, metropolitan area extends from the Rhine to the Atlantic Ocean and from the Mediterranean Sea to the English Channel and the North Sea; overseas territories include French Guiana in South America, Saint Pierre and Miquelon in the North Atlantic, the French West Indies, and many islands in Oceania and the Indian Ocean. Due to its several coastal territories, France has the largest exclusive economic zone in the world. France borders Belgium, Luxembourg, Germany, Switzerland, Monaco, Italy, Andorra, and Spain in continental Europe, as well as the Kingdom of the Netherlands, Netherlands, Suriname, and Brazil in the Americas via its overseas territories in French Guiana and Saint Martin (island), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Massif Central
The (; oc, Massís Central, ; literally ''"Central Massif"'') is a highland region in south-central France, consisting of mountains and plateaus. It covers about 15% of mainland France. Subject to volcanism that has subsided in the last 10,000 years, these central mountains are separated from the Alps by a deep north–south cleft created by the Rhône river and known in French as the ' (literally "Rhône furrow"). The region was a barrier to transport within France until the opening of the A75 motorway, which not only made north–south travel easier, but also opened access to the massif itself. Geography and geology The is an old massif, formed during the Variscan orogeny, consisting mostly of granitic and metamorphic rocks. It was powerfully raised and made to look geologically younger in the eastern section by the uplift of the Alps during the Paleogene period and in the southern section by the uplift of the Pyrenees. The massif thus presents a strongly asymmet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Dome
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 are lava dome forming. The geochemistry of lava domes can vary from basalt (e.g. Semeru, 1946) to rhyolite (e.g. Chaiten, 2010) although the majority are of intermediate composition (such as Santiaguito, dacite-andesite, present day) 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. Existence of lava domes has been suggested for some domed structures on the Mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phonolite
Phonolite is an uncommon extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a variation of the igneous rock trachyte that contains nepheline or leucite rather than quartz. Its intrusive equivalent is nepheline syenite. Phonolite is typically fine grained and compact. The name ''phonolite'' comes from the Ancient Greek meaning "sounding stone" due to the metallic sound it produces if an unfractured plate is hit; hence, the English name ''clinkstone'' is given as a synonym. Formation Unusually, phonolite forms from magma with a relatively low silica content, generated by low degrees of partial melting (less than 10%) of highly aluminous rocks of the lower crust such as tonalite, monzonite and metamorphic rocks. Melting of such rocks to a very low degree promotes the liberation of aluminium, potassium, sodium and calcium by melting of f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
