Station 6: Pyroclastic flow at Fence-rail Holes

Brian Wignall, Narrator

BLM Geologist Pat Hester explains the phenomenon of pyroclastic flow.

Pat Hester, Geologist, BLM

The thick white layer exposed on both sides of the canyon at eye level is the result of a fast-moving, ground hugging avalanche of material explosively ejected from a nearby volcano.  This phenomenon is called a pyroclastic flow.

The pyroclastic-flow deposit seen here traveled about 5 miles and was about 660° F when it came to rest approximately 6 million years ago.