Rockfalls
The Canyon Grows Wider
The formation of Zion Canyon is an ongoing
process. The Virgin River below you is
responsible for the downcutting and deepening
of the canyon. But canyon widening results
from the erosion of weaker rock strata which
support the vertical cliffs you see on both sides
of the canyon. Once the supporting strata
weather and weaken, vertical cracks in the
overlying claffs begin to widen. In time, entire
slabs can break loose and come to rest on the
slopes below. Often rockfalls happen
on a small scale, but occasionally they are
large and dramatic.
On September 17, 1994, park
visitor John Roberts of St. Louis,
Missouri, took this series of
dramatic photographs while
walking this trail. He estimates
that approximately 2 1/2 minutes
elapsed between his first and
last pictures.
