Lava Beds National Monument years BP to 1,110 years BP. Some of the major Lava Flows within Lava Beds National Monument include the: Callahan Flow; Schonchin Flow; Mammoth Crater Flow; Modoc Crater Flow; and Devils Homestead Flow. Gillem Bluff, a fault scarp, was created as the region stretched and a block of earth dropped down along this fault (see Basin and Range Province). The tuff layer on top of Gillem Bluff is 2,000,000 years old, indicating the rock layers beneath are even older. The oldest lava flow from the Medicine Lake Volcano within the monument is the Basalt of Hovey Point, near Captain Jack's
Lava Lava Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from . The structures resulting from subsequent solidification and cooling are also sometimes described as "lava". The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms. A lava flow is a moving outpouring of lava created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock. The term "lava flow"