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
Types of volcanic eruptions an event on average every 2 to 3 years. The most common underwater flow is pillow lava, a circular lava flow named after its unusual shape. Less common are glassy, marginal sheet flows, indicative of larger-scale flows. Volcaniclastic sedimentary rocks are common in shallow-water environments. As plate movement starts to carry the volcanoes away from their eruptive source, eruption rates start to die down, and water erosion grinds the volcano down. The final stages of eruption cap the seamount in alkalic flows. There are about 100,000 deepwater volcanoes in the world, although most are beyond the active stage of their