How do volcanoes form calderas instead of cone-shaped peaks?

Calderas are huge volcanic depressions created when enough magma is erupted or withdrawn that the roof of the magma chamber can no longer support itself. The overlying ground collapses, often in multiple episodes, making a large basin. Calderas can be several kilometers across and may later host lakes or new volcanic cones. Famous examples include Crater Lake in Oregon, which sits in the caldera of Mount Mazama, and Yellowstone, which is also a caldera system. These structures show that volcanoes can change shape dramatically after a major eruption.