Cinder cone

Cinder cones range in size from tens to hundreds of meters tall. The pyroclastic material making up a cinder cone is usually basaltic to andesitic in composition. It is often glassy and contains numerous gas bubbles "frozen" into place as magma exploded into the air and then cooled quickly. Lava fragments larger than 64 mm across, known as volcanic bombs, are also a common product of cinder cone eruptions. Lava rarely issues from the top (except as a fountain) because the loose, uncemented cinders are too weak to support the pressure exerted by molten rock as it rises toward the surface through the central vent. Because it contains so few gas bubbles, the molten lava is denser than the bubble-rich cinders. Thus, it often burrows out along the bottom of the cinder cone, lifting the less dense cinders like corks on water, and advances outward, creating a lava flow around the cone's base. When the eruption ends, a symmetrical cone of cinders sits at the center of a surrounding pad of lava. If the crater is fully breached, the remaining walls form an amphitheater or horseshoe shape around the vent. == Occurrence ==

, Arizona Basaltic cinder cones are the most characteristic type of volcano associated with intraplate volcanism. They are particularly common in association with alkaline magmatism, in which the erupted lava is enriched in sodium and potassium oxides. Cinder cones are also commonly found on the flanks of shield volcanoes, stratovolcanoes, and calderas. However, most volcanic cones formed in Hawaiian-type eruptions are spatter cones rather than cinder cones, due to the fluid nature of the lava. The most famous cinder cone, Paricutin, grew out of a corn field in Mexico in 1943 from a new vent. in the region of Hydraotes Chaos on the bottom of the Coprates Chasma, or in the volcanic field Ulysses Colles. It is also suggested that domical structures in Marius Hills (on the Moon) might represent lunar cinder cones. == Effect of environmental conditions ==

, an extinct cinder cone in Arizona The size and shape of cinder cones depend on environmental properties as different gravity and/or atmospheric pressure might change the dispersion of ejected scoria particles. For example, cinder cones on Mars seem to be more than two times wider than terrestrial analogues Therefore, it seems that erupted amount of material is not sufficient on Mars for the flank slopes to attain the angle of repose and Martian cinder cones seem to be ruled mainly by ballistic distribution and not by material redistribution on flanks as typical on Earth. Cinder cones often are highly symmetric, but strong prevailing winds at the time of eruption can cause a greater accumulation of cinder on the downwind side of the vent. == Monogenetic cones ==

, a young monogenetic cinder cone in Arizona that began forming around the year 1075 CE Some cinder cones are monogenetic, forming from a single short eruptive episode that produces a very small volume of lava. The eruption typically last just weeks or months, but can occasionally last fifteen years or longer. Parícutin in Mexico, Diamond Head, Koko Head, Punchbowl Crater, Mt Le Brun from the Coalstoun Lakes volcanic field, and some cinder cones on Mauna Kea are monogenetic cinder cones. However, not all cinder cones are monogenetic, with some ancient cinder cones showing intervals of soil formation between flows that indicate that eruptions were separated by thousands to tens of thousands of years. == See also ==