The Crater

 A caldera is a “large volcanic crater, formed by a major eruption leading to the collapse of the mouth of the volcano”. 

The collapse of Mount Mazama, a 3,700-meter-tall volcano formed the Crater Lake caldera we see today.

As the magma rapidly released from the chamber, the roof of it collapsed, creating a bowl-shaped depression in the caldera.

The collapse occurred within hours or days and was followed by volcanic activity within the caldera. This led to the formation of (post-caldera features) like the Wizard Island!

Over the next 250 years, the caldera was filled with rain and snowmelt, forming the lake we see today. The lake level is now maintained by both precipitation and evaporation.