A lava tree mold, sometimes erroneously called a lava tree cast, is a hollow

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or un ...

formation that formed around a

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

trunk. They are created when lava flows through an area of trees, coating their exterior. The lava cools just enough to create a solid crust around the trunk, but the tree inside burns away leaving a cavity. Molds of trees may be vertical or horizontal. In many cases, mold formation requires slow moving lava, as well as enough time for the mold to chill.

Methane explosions

A unique phenomenon may occur during the formation of vertical tree molds. As the lava-encased tree burns away, the roots are heated up and generate a "producer" gas, such as

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Ea ...

. If the roots penetrate into a cavity, such as a lava tube or

tumulus A tumulus (plural tumuli) is a mound of earth and stones raised over a grave or graves. Tumuli are also known as barrows, burial mounds or ''kurgans'', and may be found throughout much of the world. A cairn, which is a mound of stones bu ...

crack, it may come into contact with

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

. Because there is a source of heat already present, the charred root or the lava itself, a methane explosion may follow if the oxygen and producer gas mixture is between 5 and 15% (volume-percent fuel).

References

{{Subterranea Volcanoes

Methane explosions

See also

References