Lava broad, shallow slopes formed from predominantly effusive eruptions of relatively fluid basaltic lava flows, to steeply-sided stratovolcanoes (also known as composite volcanoes) made of alternating layers of ash and more viscous lava flows typical of intermediate and felsic lavas. A caldera, which is a large subsidence crater, can form in a stratovolcano, if the magma chamber is partially or wholly emptied by large explosive eruptions; the summit cone no longer supports itself and thus collapses in on itself afterwards. Such features may include volcanic crater lakes and lava domes after the event. However, calderas can also form by non-explosive means
Cinder Cone and the Fantastic Lava Beds and the two Fantastic Lava Beds flows. The second Fantastic Lava Beds flow that all scientists but Diller thought had been erupted in 1851. At the Old Bench and Painted Dunes lava flows, the volcanic ash is brightly oxidized because it interacted with the lava flows when they were still hot. It shares its compositional group with the Fantastic Lava Beds flows, which represent the last flows erupted at Cinder Cone. Ultimately, the eruptive sequence at Cinder Cone took place over the course of several months. An unusual characteristic of the Fantastic Lava Beds is the presence of anomalous quartz