The ridgeline trends north, and the lower elevation cliff, the tail of the alligator, turns northwest.

Because both are cliff-formers (and therefor shelf-formers), the high-point of The Alligator is on the upper platform (shelf) of the Supai Group, the highly resistant Esplanade Sandstone.

The curved tail of The Alligator is the bottom platform, sitting on top of the highly resistant Redwall Limestone.

As the tail curves, a smaller, secondary cliff-platform (above the Redwall), is composed of Supai unit 2, the also resistant Manakacha Formation.

The rest of the Tonto Group sits on the Granite Gorge at the Colorado River with the walls of Vishnu Basement Rocks.