Just outside of Washington state’s capital city of Olympia is a mysterious land formation – the Mima Mounds. The Mima Mounds are hundreds of small hills dotting the area in a way that seems too uniform for any real explanation you might come up with. No one knows for sure what created this lumpy landscape, but there are several theories and it’s a lot of fun to speculate as you visit. Glaciers? Giant gophers? Aliens? Who knows! (I’ll include some of the major theories below, if you’re nerdy like me and want to know what these things might be).
The Mima Mounds are a great spot to visit with the fam. The trails are flat and level so tiny feet can handle them whether you walk up to the viewing platform, or head out to tackle one of the trails. They’re open all year round, but are especially awesome to visit in the spring or early summer when wild flowers are popping. We visited in mid-June and daisies and tiny purple flowers and dandy lions covered the hills – super pretty!
So what exactly are the Mima Mounds?
The Mima Mounds are essentially a prairie, but a prairie filled with hills. Some were taller than we were, others were our height or less. The mounds were designated a Registered National Landmark in 1966 and are protected and maintained. No one knows exactly what all these mounds are doing here, though, but there are more than 30 running theories.
A quote on a display reads: “The Mima Mounds have given rise to many diverse explanations of their origin. Hardly any other land form has stimulated so much controversy in geologic and natural science.” The quote is by Arthur Kruckeberg, an author, botanist at professor at the University of Washington who was an advocate for protecting the mounds.
Of the more than 30 proposed theories, none have been proven. Some of these include that the mounds were formed by glaciers, by earthquakes, by erosion while plants were still anchoring the soil to form mounds around the now-gone plants, pocket gophers (with the center of each mound being the center on a single pocket gopher’s territory), or cracking permafrost. The plaques at the viewing center did not include any theories about aliens, but I really feel like they’re missing out there.
Scientists do know that the Mima Mounds were formed around the time ice age glaciers began retreating about 16,500 years ago.
What can you do there?
From the parking area, follow the paved trail (that part is important – we didn’t spot it at first, but you should stay off of the ground while you’re here to keep it protected and instead look for graveled or paved pathways) and you’ll reach the viewing platform. It’s tough to miss as it is the only structure here and it’s definitely not a Mima Mound, even though it has a rounded top and it’s obviously trying to blend in.
The viewing platform has a number of displays where you can read up on the native plants in the area, about how prairies depend on fire and active management, as well as some of the Mima Mound theories.
You can also climb a set of stairs and get a better overview of the mounds and how far out they go.
I read ahead of our visit that on clear days you can see Mt. Rainier and even Mt. St. Helens, but it was decently clear when we were there and I saw no mountains. I’m not sure where you’ll need to stand to spot them.
If you want to venture out among the mounds, there are several trails to explore. All are flat and easy to walk, but as this is a prairie, they are also completely exposed to the sun. Bring along some water and hats unless you enjoy the sun beating down on you (like a good Northwesterner, I don’t and I start to wither within minutes of sun exposure).
From the viewing platform, you can head south and you’ll find a stretch of trail winding through the mounds. Follow that and you’ll come to a junction where you can continue on to either a 1-mile loop trail or a 1.9-mile loop trail.
If you head north from the viewing platform, you’ll find an ADA wheelchair accessible trail as well as a 0.5-mile North Loop.
All trails are fairly flat and level. Some are paved and some are gravel. My two-year-old was able to traverse them all without problems. She also enjoyed the daisies lining the sides of the paths.
How do you get to the Mima Mounds?
From southbound or northbound I- 5, take exit 95 and turn west on Highway 121 (Maytown Road SW) toward Littlerock.
In Littlerock, keep going west past the intersection with Littlerock Road and past the mini mart and gas station on the right until you get to 128th Avenue.
Keep going about 0.8 mile where 128th Avenue ends at a T junction and then turn right onto Waddell Creek Road.
Go about 1 mile. The entrance to Mima Mounds Natural Area Preserve will be on the left.
I recommend just busting out the GPS because I tried to follow along with instructions I’d found online and kept feeling like I’d missed a turn as it’s located in a fairly rural area.