bomb sag

Quick Reference

The deformation of primary, unconsolidated, volcaniclastic bedding structures by the impact of a large ballistic block. The block, which can be a volcanic bomb or a fragment of crystalline country rock, is ejected from its source vent during a period of violent explosive activity. The asymmetry of the deformation structure it produces can be used to locate the position of the source vent.

Subjects: Earth Sciences and Geography.

Reference entries