What is the name of the large depression formed at the top of a volcano when the roof of its magma chamber collapses?

The large depression formed at the top of a volcano when the roof of its magma chamber collapses is known as a caldera. When a volcano erupts, it can expel a significant amount of material from the magma chamber, which can result in a decrease in pressure and support for the volcanic structure above. Eventually, this can lead to the roof caving in, creating a broad, often circular depression. Calderas can vary in size and may be several kilometers wide, making them distinct geological features.

Understanding the processes leading to the formation of a caldera helps clarify its characteristics, such as its typically large scale and the way it can encapsulate the remnants of volcanic activity. The other terms, such as glacier, laccolith, and valley glacier, refer to different geological or geomorphological features that do not involve the collapse of a volcano's structure. A glacier pertains to a large ice mass formed from snow, while a laccolith is a dome-shaped intrusion of magma that has forced its way between rock layers, and a valley glacier is a type of glacier flowing down a mountain valley.