Traveling out I40 is really amazing as the terrain. Each state seems to have it's own contour....out in western Oklahoma - it's really really flat.
And the minute we hit the TX/NM border the mesas start to appear.
And the out of NM into AZ the sky seems to get bluer and the earth turns amazing colors.
This is the beginning of the Grand Staircase which shows the 6 steps of the staircase - from top to bottom: Pink Cliffs (Bryce NP), Grey Cliffs, White Cliffs, Vermilion Cliffs (Kanab, UT), Chocolate Cliffs and the Grand Canyon.
You can not tour this part of the world and not get interested in geology.