Caldera

A caldera is a landscape-scale clue to events beneath the surface. It is not simply another name for any hole at a volcano's summit. The depression can outlast the eruption that formed it, acquire new volcanic features and eventually contain a lake.

Start with the outline: where is the rim, what interrupts it, and what occupies the space inside? Then look for later additions. An island or dome can record activity after the main collapse. Water, vegetation and erosion can soften the impression without removing the underlying volcanic structure.

A compelling photograph may make such a place appear timeless. The scientific interest comes from reconstructing a sequence of change. The diagram in Earth Lab is deliberately schematic; a real caldera has a more complicated history than one simple animation can show.

Further explanation and context: www.nps.gov. The examples below are editorial connections, not a claim that every place has an identical history or form.