Not all lava trees are standing. When lava surged through the forest, some trees were pushed over by the force of the flow. Those snapped off wore carried away, molds formed around some of these. Others remained, anchored by their roots. An aerial view of Newberry Volcano shows many fissures leading away from the mountain.
Fissures are lines of weakness in the Earth's crust.
Volcanic activity occurs along fissures because it is easier for magma to push its way toward the surface. Parts of the Lava Cast forest flow, Cascade Flow, and forest Road Flow are included in the Lava Cast Forest Geologic area. Recent work done on flow contacts has shown that all three flows are from the same short eruptive phase, refuting an earlier belief by geologists that each flow happened at a different time. Lava along the first half of the trail came from the fissure's north end. Lava gradually cooled and hardened.