Cinder cones build up from lava fragments thrown into the air and deposited around a vent. The material called scoria contains bubble-shaped cavities. Lassen’s Cinder Cone illustrates a steep, compact hill rather than a broad volcanic mountain.
Look for the cone’s shape and granular slopes, then compare it with the surrounding terrain. Lava can also emerge near a cone’s base, so a field of flows need not come from the summit crater. This entry connects a landform with the pieces that build it.
Source / photo: NPS · Public domain. Resized. No claim to original U.S. Government works.