Cinder Cone and the Fantastic Lava Beds edifice. The summit of Cinder Cone has a crater with a double rim (photo), probably created by two different phases of one eruptive period. The cone also has a widespread ash deposit identifiable for from the cone. Blocks of red, cemented scoria within the Painted Dunes lava flows (photo) are pieces of this earlier cone, which were carried away by the flowing lava. When Cinder Cone formed, the magma feeding the eruption changed composition, shifting from basaltic andesite to andesite before returning to basaltic andesite with increased titanium content. While basaltic andesites are volcanic rocks containing 53 to 57% silica,
Lava River Cave ago. The source is believed to be near Mokst Butte southeast of the entrance. The same volcanic flow that formed the cave underlies much of the Bend area and almost reaches Redmond, Oregon. However, the specific vent that created the cave has been buried by several younger flows. The Lava River Cave was created by lava flowing downhill from a volcanic vent. The lava flowed northwest from the vent toward the Deschutes River. The flow began as a river of lava flowing in an open channel. Eventually, a lava crust solidified over the top of the flowing lava. This formed