Which of the following is not a volcanic feature?

Volcanoes are formed when magma, ash, and gas escape from a magma chamber and rise to the Earth's surface. There are several types of volcanic features that are formed by this process. A ventifact is not a volcanic feature. A ventifact is a geological feature that is formed by the erosive action of wind-blown sand on rocks. Over time, wind-blown sand can abrade rocks and create unusual shapes and formations. Therefore, the answer is: Ventifact. Ventifacts are not related to volcanic activity and are formed by the action of wind on rock surfaces, while calderas, geysers, and dykes are all volcanic features formed by the movement of magma and other volcanic material.