Kulshan caldera

[1][2] It is the product of the Mount Baker volcanic field, which has a history stretching back to possibly 3.722 million years ago.

Formation of the caldera about 1.149[3] million years ago was accompanied by the largest eruption in the history of the Mount Baker volcanic field.

[6] As the magma escaped from the shallow reservoir, the rock above it collapsed downward forming a massive 4.5 x 8 km (2.8 x 5 mi) depression.

Another volcanic phase 1.1 to 0.5 million years ago emplaced over 60 andesite dikes, the eruptive products of which have since been stripped away by glacial erosion.

[9] Media related to Kulshan Caldera at Wikimedia Commons This article incorporates public domain material from websites or documents of the United States Geological Survey.