Calderas are best described as what?

• A. Active craters formed by eruption
• B. Mountain peaks formed by uplift
• C. Collapsed volcanoes
• D. Volcanoes with lava domes

Answer: (C)

Calderas are large volcanic depressions formed when a magma chamber is largely emptied during a major eruption and the volcano’s summit collapses into the emptied space. That collapse creates the broad, basin‑like feature that characterizes a caldera, so describing it as a collapsed volcano captures the essential idea. An active crater is just an eruptive opening at the surface, not the result of a wide summit collapse. Mountain peaks formed by uplift come from tectonic forces pushing land upward, not from collapse after magma drained. Lava domes describe specific mounded features of viscous lava that can occur inside or near volcanoes, but they don’t define the overall caldera structure.