Cinder cone

[2][3] The pyroclastic fragments are formed by explosive eruptions or lava fountains from a single, typically cylindrical, vent.

As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as either cinders, clinkers, or scoria around the vent to form a cone that often is symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan.

[8] 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.

[3] For example, geologists have identified nearly 100 cinder cones on the flanks of Mauna Kea, a shield volcano located on the island of Hawaii.

[3] Eruptions continued for nine years, built the cone to a height of 424 meters (1,391 ft), and produced lava flows that covered 25 km2 (9.7 sq mi).

[13] On Mars, they have been reported on the flanks of Pavonis Mons in Tharsis,[14][15] in the region of Hydraotes Chaos[16] on the bottom of the Coprates Chasma,[17] or in the volcanic field Ulysses Colles.

[19] 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.

[11] Some cinder cones are monogenetic, forming from a single short eruptive episode that produces a very small volume of lava.

[21] Monogenetic cones likely form when the rate of magma supply to a volcanic field is very low and the eruptions are spread out in space and time.