Cinder Cone

Cinder Cone, small volcanic mountain (see Volcano) formed by the accumulation of rock or mineral fragments, called pyroclasts, that are ejected during explosive volcanic eruptions. Cinder cones are steep-sided, often symmetrical mountains that match the popular expectation of what a volcano should look like. These distinctive cone-shaped landforms appear in many areas of the world.

The rock pieces, or cinders, that form cinder cones are primarily fragments of basalt, a dark-colored rock. During an eruption, the force of volcanic gases ejects the cinders into the air. The cinders fall and pile up into a cone shape around the volcano. A cinder cone is relatively small because the accumulation of loose cinders creates an unstable pile of debris, prone to collapse under its own weight. Generally not more than 500 m (1600 ft) high, cinder cones are much smaller than the other general types of volcanoes, stratovolcanoes and shield volcanoes, which are usually several thousand meters high. Stratovolcanoes and shield volcanoes usually erupt over longer periods and not as explosively as cinder cones, allowing the lava flows to accumulate in layers and create larger, more stable volcanoes over time. Most cinder cones are considered monogenetic volcanoes, meaning that they erupt only once for a short period and then become extinct. These eruptions rarely last for more than tens of years. In contrast, shield volcanoes and stratovolcanoes are considered polygenetic volcanoes, because they are capable of repeated eruptions—separated by inactive periods called dormancy—over hundreds of thousands of years.

Cinder cones are located throughout the world, including the western United States, Iceland, and Mexico. Some of the best examples of monogenetic cinder cones are found in the Trans-Mexican Volcanic Belt, a volcanic region that extends across central Mexico. Two historical eruptions that formed new volcanoes occurred in this region: the Jorullo eruption during the period from 1759 to 1774, and the well-documented Paricutín eruption, from 1943 to 1952. The Jorullo eruption created a volcano that grew 250 m (820 ft) during its first six weeks of eruption. The Paricutín eruption resulted in the birth of a volcano in a cornfield about 300 km (200 mi) west of Mexico City. Most of Paricutín’s growth occurred within the first year of its eruption. By the end of 1943 the cone had grown more than 336 m (more than 1100 ft). When the eruption ceased in 1952, the cone stood about 410 m (about 1350 ft) above its base, and its total elevation was 2774 m (9101 ft) above sea level. Other than the well-studied Paricutín cinder cone and its associated lava flows, scientific observations of cinder cone formation are scarce.