The names of the formations are written on the illustration, but not legible on the reproduction. They are listed below, along with their age estimates, mostly in millions of years. A single age is given for the Supai Group, which consists of the four formations from Esplanade to Watahomigi.
The oldest rocks of the Grand Canyon are the Zoroaster Granite and Vishnu Schist. They are not seen from this part of the river.
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