• Blue Mesa: A little farther afield, Blue Mesa is the least visited and most overlooked location in the park, Larsen said. "It's one of my favorite spots," she said. "Relatively few people go there."

The area is about a 10- to 15-minute side trip from the main road, but it offers gorgeous views of badlands, log falls and pedestal logs. It includes an optional one-mile strenuous walk. Blue Mesa will have new exhibits this year, Larsen said.

• The Tepees. Some visitors may have their fill of petrified wood at this point of a visit. However, along the road are the "Tepees" — colorful formations layered in gray, red and white that rise sharply above the landscape and are a photographer's delight.

• Puerco Pueblo. Puerco Pueblo is a stabilized 100-room structure may have housed as many as 1,200 people between 1250 and 1380 A.D. The village's residents also inscribed interesting, even odd, petroglyphs on the sides of nearby stones. (One shows what appears to be a giant bird with what may be a human in its long beak.)

The river nearby provided water for the Puerco people, for animals and for farming — corn, cotton, squash and beans, according to archaeologists.

• Newspaper Rock. Just up the road, Arizona's Newspaper Rock is worth a visit since it overlooks an area with a striking number of petroglyphs: spirals, human shapes and stick figures, winged or feathered creatures — more than 650 of them by one count. Spotting scopes make the viewing easier, for the boulders and cliff sides are fenced off and far below.

"People who farmed the Puerco River Valley 650 to 2,000 years ago pecked these petroglyphs onto the rocks, leaving a legacy etched in stone," a marker notes. In 1975 the site was added to the National Register of Historic Places.

• The Painted Desert. On the north flank of I-40 lie the Painted Desert and the park's northern visitor center.

Five roadside viewpoints showcase the desert beyond, seemingly painted with a red-dominated palette. Chinde Point, directly above the Black Forest, is the centerpiece, but there are also eroded wonders to be seen at points such as Kachina (which also hosts the Painted Desert Inn Museum), Pintado, Nizhoni and Tiponi.

Again, placards offer insight into the area's history, including exploration by Lt. Amiel Whipple, surveying a potential railroad route in 1853, and Edward Fitzgerald Beale's work establishing I-40's mid-19th-century precursor, the Beale Wagon Road. Other signs explain the area's bleak but beautiful geology, rumpled badlands eroded into hillocks, ridges and gullies.