You’re driving down Rosecrans Avenue, stuck in that familiar North Orange County traffic, and you see a wall of sandstone cliffs. It looks like something out of a Western movie, tucked right between the suburban sprawl of Buena Park and Fullerton. That’s Ralph B. Clark Regional Park. Honestly, most people just see the grass and the lake and think, "Cool, a place to walk the dog."
They’re missing the best part.
Beneath your sneakers is one of the densest fossil beds in the United States. We aren't just talking about a few old shells. We’re talking about mammoths, giant ground sloths, and 9-million-year-old whales. This isn't just a park; it’s a prehistoric graveyard that only exists because a highway crew started digging for gravel in the 1950s.
The Weird History of the Emery Borrow Pit
Back in the day—we're talking 1956 to 1973—this place wasn't a park. It was the Emery Borrow Pit. The California Division of Highways (now Caltrans) needed dirt and gravel to build the Santa Ana (I-5) and Riverside (SR-91) Freeways.
They dug. And dug.
As the machines tore into the earth, they started hitting bone. Big bone. Scientists realized they’d stumbled onto a goldmine of the Pleistocene and Miocene epochs. The public actually had to fight to save this land from being filled in or paved over. By 1974, the County of Orange snagged it. It opened in 1981 as Los Coyotes Regional Park before being renamed in 1987 to honor Supervisor Ralph B. Clark.
✨ Don't miss: Weather at Kelly Canyon: What Most People Get Wrong
That Whale in the Middle of the Park
If you visit, you have to hit the Interpretive Center. It’s a small museum, kinda hidden, but it’s nationally recognized. Inside, there's a 9-million-year-old baleen whale nicknamed "Joaquin."
Imagine Orange County underwater.
Because it was. Joaquin was found during the construction of the San Joaquin Hills toll road and eventually moved here. It’s one of the only complete Miocene whale fossils in existence. You can also see the "fishbowl lab" where volunteers actually prep fossils. It’s not some stale, dusty exhibit; it’s a working paleontology site.
What else is in the dirt?
- The largest collection of fossilized pond turtles in Southern California.
- Ring-tailed cats and ancient llamas (yes, llamas used to live in OC).
- Ice Age giants like the Columbian mammoth and the Harlan’s ground sloth.
Real Talk on Fishing and Sports
Okay, maybe you don't care about old bones. You just want to catch a fish. The three-acre lake is stocked with catfish and trout during the cooler months. You’ll see people lined up along the shore with lawn chairs and coolers.
It's chill.
🔗 Read more: USA Map Major Cities: What Most People Get Wrong
Just a heads-up: if you’re 16 or older, you need a California fishing license. No exceptions. The rangers do check. For the kids, though, it’s a great "first fish" spot.
The park is split by Rosecrans Avenue. The south side is where you find the lake, the museum, and the big shaded picnic spots. The north side, often called "The Yard," is the sports hub. As of April 2025, ZT Parks took over the management of the 14-acre Clark Sports Complex. It’s got six fields for baseball, softball, and soccer. If you've ever played travel ball in Southern California, you've probably spent a dusty Saturday here.
Hiking the Sandstone Cliffs
The 1.2-mile perimeter trail is the park's secret weapon. It’s an easy loop, but if you take the spur up to the top of Camel Hill, the view is massive.
On a clear day? You can see Catalina Island. You can see the Long Beach port. You can see the KFI radio tower and the snow on Mount Baldy. It feels completely disconnected from the shopping centers just a mile away.
The sandstone cliffs themselves are fragile. Don't be that person trying to climb them or carve your name into the rock. It's actually illegal, and more importantly, it ruins the very thing that makes the park look so distinct.
💡 You might also like: US States I Have Been To: Why Your Travel Map Is Probably Lying To You
Things You Actually Need to Know
Parking isn't free. Usually, it’s $3 on weekdays and $5 on weekends. Holidays can be higher. If you're cheap (no judgment), you can technically find street parking nearby and walk in, but the lot is right there.
The Interpretive Center has weird hours. It’s generally open Wednesday through Saturday, 10 a.m. to 2 p.m. Don't show up on a Monday expecting to see the whale; you’ll just be staring at a locked door.
If you have kids, look for the "Preschool Paleontology" programs. They’re super popular and usually involve art and storytime. For the adults, the "Explore! Fossils of the Ancient Sea Floor" guided hikes are the way to go. You get to see the actual hillside where stuff is still being found.
Actionable Tips for Your Visit
- Check the Schedule: Call the park office at (714) 973-3170 before you go if your main goal is the museum. Staffing can be hit or miss.
- Bring a Picnic: The shaded areas are huge and have actual charcoal grills. It’s way better than eating at a fast-food joint nearby.
- Watch the Sun: If you’re hiking the perimeter trail, there isn't much shade on the upper ridge. Go early or late.
- License Up: If you plan to fish, buy your license online beforehand. There isn't a bait shop in the park that sells them.
Ralph B. Clark Regional Park is a weird, beautiful mix of a neighborhood hangout and a world-class scientific site. Whether you're there for the softball tournament or the 9-million-year-old whale, it’s worth more than just a drive-by.