Lava Beds National Monument Stronghold, which is 450,000 years old. Petroglyph Point was created about 275,000 years ago when cinders erupted through the shallow water of Tule Lake; violent explosions of ash and steam formed layers upon layers of tuff. The caldera is thought to have formed by subsidence, during which basalt and andesite were erupted up on the slopes. Lava flows dated to about 30,000–40,000 years ago formed most of the lava tube caves in the monument. As the hot basaltic lava flowed downhill, the top cooled and crusted over, insulating the rest of the lava and forming lava tubes. Lavacicles on the
Ice-marginal lava flow its subglacial beginnings. Currently the volcano is surrounded on all sides, except the south, by glaciers. What does Hoodoo mountain have to do with ice-marginal lava flows? Well, the entirety of the mountain is also surrounded by enormous lava cliffs, ranging from 50m-200m in height, as seen in Figure 3. The clearest example of these lava cliffs is seen on the southwestern side of the mountain whereas the northern formation of these cliffs has been overridden by recent lava flows and glacial erosion. Scientists are able to diagnose these lava cliff formations as a result of ice-marginal lava flows because