How Volcanoes Work

 Image Described in Caption Flow inflation and tree molds -- Lava from a pahoehoe sheet flow has chilled and solidified around tree trunks on the Kilauea Volcano, Hawaii, to produce hollow tree molds (the trees have been incinerated). The pahoehoe sheet flow inflated to the highest level on the tree mold. It then deflated as lava drained away beneath the solidified pahoehoe crust. Courtesy of C. Heliker, USGS.