Illustrated Volcano Glossary

The lava coating around a tree trunk left by an invading liquid lava flow.

When a liquid lava flow invades a forest, often, the lava does not overthrow the larger trees, but flows around their trunks. At the very contact of the hot lava to the bark, a thin layer of the lava is quenched sufficiently to form an isolating coating around the trunk. The tree itself most often burns down slowly, eventually falling down onto the lava.
The typical lava trees are formed when after the initial surge, the lava level drains and lowers, but the earlier chilled coating around the trunk is behind standing as a precise hollow cast of lava around the shape of the original tree up to the highest lava level during the eruption.
In some cases, the tree can even remain standing and remain for years as a black charred skeleton, and in rare cases, some trees even survive and continue to grow after the eruption.
Lava trees are typically found at basaltic shield volcanoes with liquid lava flows such as Kilauea on Hawaii.