Central Oregon's John Day Fossil Beds National Monument is a colorful wonderland of painted hills and geologically preserved prehistoric species.

FOSSIL, Ore. — Rebecca Buss does taxes for a living, so by the end of April, the Tri-Cities resident was ready for a road trip. “I needed to get somewhere, get out of the office and into the ground,” Buss said. Her daughter, Felicity, had an idea to do exactly that, based on a tip from a fellow Girl Scout.

That’s how Rebecca, husband David and Felicity found themselves on a hillside in Fossil using gardening tools to carefully pry apart layers of shale, looking for the fossilized remains of ancient alder and maple leaves.

The Northwest is a layer cake of geology, where land was formed by one explosion, ash cloud or oozing lava flow after another. What is now Oregon didn’t exist until about 60 million years ago, when the first volcanoes laid down new terrain over an ancient ocean bed.

Over and over, volcanic material swept through, burying and preserving plants and animals. This makes central Oregon’s John Day Fossil Beds National Monument one of the world’s richest mammal-fossil troves.

Not just T. Rex

Fossils don’t just mean dinosaurs. This area always has been home to the mammals that emerged with the dinosaurs’ decline 65 million years ago.

What used to live here? Oversized burrowing rodents with bony ridges on their heads, 700-pound pig-

like animals with massive teeth, and giant saber-toothed cats, for starters.

Some animals — ancestors of today’s camels, horses, elephants and rhinoceroses — originated here, crossed land or ice to other continents and then disappeared from North America.

In the monument, you can start to wrap your mind around that kind of history. Its three spread-out units — Clarno, Painted Hills and Sheep Rock — are diverse, but all have restrooms, picnic areas and a handful of short walks or hikes, often with interpretive signs.

“I tell people you need at least two days” to explore the monument, said Anne Mitchell, executive director of the Oregon Paleo Lands Institute. “All three are unique in terms of their geology and the fossil record.”

The institute lost funding during the recession, and operations are shut down for now. But Mitchell still volunteers and takes private tours to fossil-rich spots in and around the monument.

Here’s a brief tour, starting with the oldest exposed geology (reverse this order to see the visitor center first).

Condon and Clarno Unit

We started in the town of Condon, where buildings are made of sturdy local brick, and equally sturdy families farm amid vast skies, rolling wheat fields and sagebrush-covered hillsides.

Surprisingly, the tiny hamlet sports the boutique Hotel Condon and a decent restaurant, the Round-Up Grill, which opened just a few weeks ago (as with many places around here, the desserts are homemade and decadent).

Just down the road from Condon, Fossil is the first stop in the regional tour. Behind Wheeler High School, on a hillside dug out for an athletic field, a shale-covered slope is awash in fossils.

Borrow some tools from the shack on the school’s far side (donations fund school programs) and use them to gently separate rock layers. The Buss family found a half-dozen or so fossils before rain forced them off the hill.

The national monument’s Clarno Unit, 20 miles southwest of Fossil, is the site of an ancient mudslide that trapped thousands of fossils, including plant fossils indicating this was then a tropical place. It takes only about an hour to explore, depending on whether you take one or both of the half-mile walks along the base of spiky volcanic cliffs called the Palisades.

Painted Hills Unit

and Mitchell

The Painted Hills might be the most photographed attraction in the national monument, and for good reason: The hills look like sand paintings, with stripes of red and gold along their flanks. As well as the usual short trails — to viewpoints or along a boardwalk around bright-red rock piles at Painted Cove — there’s a short, steep slog, Carroll Trail, that makes for a quick workout with nice views at the top.

The closest town is Mitchell. For better or worse, it feels like its own trip back in (more recent) time, but there’s lodging and dining (if you don’t turn up too late in the evening).

Sheep Rock Unit

and Blue Basin

The monument’s Sheep Rock Unit is home to the Thomas Condon Paleontology Center, an essential stop. Its displays of locally sourced fossils and models of ancient plants, animals and landscapes help visitors grasp the progression of ancient history.

The other must-do stop in the Sheep Rock Unit is Blue Basin, a canyon carved out of a hillside near the visitor center.

The cliffs’ turquoise color, a result of their distinct mineral composition, is both surreal and oddly beautiful. “You walk in there and you think Captain Kirk and his crew should be there battling aliens,” Mitchell said.

When it rains, blue-green silty water flows down a seasonal stream alongside the half-mile trail into the canyon.

The three-mile Overlook Trail goes above and around the basin and is steep in places; if you’re going to do both trails, the best way is to do the overlook trail clockwise and end with a foray into the canyon.

Christy Karras is a Seattle-based freelance writer.