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Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust.
Serpentinization is thought to produce approximately 80% of the world's hydrogen, especially as seawater interacts with iron- and magnesium-rich (ultramafic) igneous rocks in the ocean floor. Current models point towards radiolysis as the source of most other natural hydrogen.
The English designation Agathla is derived from the Navajo name aghaałą́ meaning 'much wool', apparently for the fur of antelope and deer accumulating on the rock. [3] The mountain is considered sacred by the Navajo. Agathla Peak is an eroded volcanic plug consisting of volcanic breccia cut by dikes of an unusual igneous rock called minette.
The Giant's Causeway (Irish: Clochán an Aifir) [1] is an area of approximately 40,000 interlocking basalt columns, the result of an ancient volcanic fissure eruption. [3] [4] It is located in County Antrim on the north coast of Northern Ireland, about three miles (4.8 km) northeast of the town of Bushmills.
Diorite (/ ˈ d aɪ. ə r aɪ t / DY-ə-ryte) [1] [2] is an intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composition between low-silica gabbro and high-silica granite.
It is an igneous rock. [6] Produced from felsic lava, obsidian is rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. These flows have a high content of silica, giving them a high viscosity.
Erosion usually exposes the geological formations, which are often made of very hard and solid igneous or metamorphic rock. Some monoliths are volcanic plugs , solidified lava filling the vent of an extinct volcano .
This is an accepted version of this page This is the latest accepted revision, reviewed on 16 January 2025. Mountain in South Dakota with sculptures of four U.S. presidents For the band, see Mount Rushmore (band). Mount Rushmore National Memorial Shrine of Democracy Tȟuŋkášila Šákpe Mount Rushmore features Gutzon Borglum's sculpted heads of George Washington, Thomas Jefferson, Theodore ...