the grand canyon looking down from the summit.

wilderness tree nature rock mountain landscape autumn valley geology park trail plant canyon adventure leaf forest terrain ridge grand summit fallen trees live pines frame canyo clouds sky earth#39aph39#s geological colorado river tributaries channels layer plateau uplifted incision geologists driven down-cutting retreat cliffs deepening widening inhabited native americans caves pueblo pilgrimages viewed national tourists tourism hiking camping trails views • glen • gulch • coulee gorge ravine gully rim