Very distinct layers of white and blue. If I understand correctly, the dark blue/purple is due to bentonite clay.

The Triassic aged rocks in the park are assigned to the Chinle Formation and consist mainly of sand, mud, and gravel that were deposited by a large river system from 225 to 205 million years ago.
During this time the area that is now Petrified Forest National Park was located along the western coast of the supercontinent Pangaea and located approximately four degrees above the equator, roughly equivalent to modern-day Panama!