Volcanic cone

Volcanic cones are of different types, depending upon the nature and size of the fragments ejected during the eruption.

[1][2] Stratocones are large cone-shaped volcanoes made up of lava flows, explosively erupted pyroclastic rocks, and igneous intrusives that are typically centered around a cylindrical vent.

This central core is surrounded by multiple generations of lava flows, many of which are brecciated, and a wide range of pyroclastic rocks and reworked volcanic debris.

They are characterized by high rims that have a maximum relief of 100–800 meters (330–2,620 ft) above the crater floor and steep slopes that are greater than 25 degrees.

A tuff cone consists typically of thick-bedded pyroclastic flow and surge deposits created by eruption-fed density currents and bomb-scoria beds derived from fallout from its eruption column.

[2][5] A tuff ring is a related type of small monogenetic volcano that is also produced by phreatic (hydrovolcanic) explosions directly associated with magma brought to the surface through a conduit from a deep-seated magma reservoir.

The pyroclastic materials that comprise their rim consist primarily of relatively fresh and unaltered, distinctly and thin-bedded volcanic surge and air fall deposits.

Their rims also can contain variable amounts of local country rock (bedrock) blasted out of their crater.

As a result, water commonly fills a tuff ring's crater to form a lake once eruptions cease.

The interaction between the magma, expanding steam, and volcanic gases resulted in the production and ejection of fine-grained pyroclastic debris called ash with the consistency of flour.

[1][8] They consist of loose pyroclastic debris 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 noticeably symmetrical; with slopes between 30 and 40°; and a nearly circular ground plan.

Of observed cinder cone eruptions, 50% have lasted for less than 30 days, and 95% stopped within one year.

Littoral cones typically form on the surface of a basaltic lava flow where it has entered into a body of water, usually a sea or ocean.