Criteria for Recognit

“Megabreccias”Evidence for Extension and Subsidence• Megabreccia – is a breccia, typically heterolithologicand comprised of clasts that range in size from lapilli,to large metre-sized to kilometre-sized blocks. Thebreccia is massive, poorly sorted, but can be crudelylayered.• Forms during initial caldera collapse and includelithologies exposed on the caldera walls/margins, aswell as juvenile components.