One more shot: notice the hole cut in the cliff above. This is a window from the CCC-built tunnel that travels from Zion Valley to the East rim, skirting the cliff face at several times. We don't know if this is because they accidentally kept poking out of the mountain when building the road, or whether they simply wanted to provide some light (and a view) in the otherwise unlit tunnel. In any case, no stopping is allowed so these windows are just blinding-white occasional blurs as you drive through the tunnel.