| Mima Mounds Natural Area Preserve | |
|---|---|
 Mima Mounds in May of 2023 | |
   Interactive map of Preserve location | |
| Location | Southwest corner of Thurston County, Washington, United States |
| Nearest town | Littlerock, Washington |
| Coordinates | 46°53′N 123°03′W / 46.89°N 123.05°W |
| Area | 756 acres (306 ha) |
| Established | 1976[1] |
| Governing body | Washington Department of Natural Resources |
| Website | www |
Mima Mounds Natural Area Preserve is a state-protected Natural Area in the southwest corner of Thurston County, Washington, on the outwash plain of the Vashon Glacier.[2] It was established in 1966 to protect examples of mima mounds.
History
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The mounds were formed approximately 15,000 years due to glacial retreat. Indigenous people used controlled burns at the site to maintain the landscape as a prairie, allowing vegetation used for food or medicine to prosper.[3] The mounds were documented by Charles Wilkes on May 20, 1841, who speculated they were burial sites.[4][2]
In 1966, the mounds were designated a National Natural Landmark. The origins of the word, mima (MY-ma), is unknown.[3]
Geography
[edit]The mounds were once part of a larger stretch of a prairie ecosystem encompassing approximately 180,000 acres (73,000 ha), spanning from present-day Joint Base Lewis–McChord through Chehalis and into Oakville. The preserve is located between Capitol State Forest and the community of Littlerock.[3]
Features
[edit]There are approximately 8-10 mounds per acre, measuring 1–7 feet (0.30–2.13 m) in height and having a diameter of 8–40 feet (2.4–12.2 m).[5][6]
Ecology and environment
[edit]The landscape contains natural vegetation such as Camas lilies, huckleberry, Indian plum, and salal. The mounds are usually covered in various shades of lichen and moss. Gophers are native to the area since the glaciers retreated.[3] The site contains 756 acres (306 ha) of Garry oak woodland, oak savanna, and prairie grasslands.[1][7]
Golden paintbrush, once common on the prairie and at the preserve, is considered a threatened species. Invasive plants include Douglas fir and Scotch broom.[3]
Butterflies
[edit]The preserve is host to wildflowers and many species of butterfly (some endangered), with activity between spring and early fall, mid-morning and mid-afternoon.[8]
- Common wood-nymph
- Coenonympha tullia
- Vanessa cardui (rare; migratory)
- Vanessa atalanta
- Lorquin's admiral
- Boloria epithore (late April-May)
- Speyeria zerene
- Euphydryas editha taylori (endangered[9])
- Polites mardon (endangered[10])
- Polites sonora (late May-August)
- Ochlodes sylvanoides
- Papilio zelicaon (May, July-August)
- Papilio eurymedon (April-October)
- Papilio rutulus
- Anthocharis sara
- Callophrys augustinus
- Callophrys polios
- Icaricia icarioides blackmorei
- Glaucopsyche lygdamus (March-June)
- Great spangled fritillary (early June-August)
- Holly blue
- Parnassius clodius
- Monarch butterfly (rare; not native to region)
Recreation
[edit]A short, ADA-accessible 0.5 mile paved trail leads to a small interpretive shelter and observation deck with view of the prairie.[6] A longer, unpaved gravel 1.5 mile loop trail to the south explores the mounds with possible views of Mount Rainier and Mount St. Helens.[11][12]
Gallery
[edit]-
NPS plaque designating the landmark. -
Trees and mounds in May 2023. -
Picnic area with view of mounds in March 2021. -
Observation structure with information graphics.
See also
[edit]
References
[edit]- ^ a b "Mima Mounds Natural Area Preserve". Washington State Department of Natural Resources. Retrieved June 16, 2025.
- ^ a b "Mima Mounds Illustrations". faculty.washington.edu. Retrieved June 16, 2025.
- ^ a b c d e Seven, Richard (July 6, 2008). "Mima Mounds: Mystery hides in vast prairie". The Seattle Times. Retrieved July 22, 2025.
- ^ "Mima Mounds: The Mysterious Work of Nature Historical Marker". Historical Marker Database. Retrieved June 16, 2025.
- ^ Kresge, Joanna (July 17, 2024). "Investigating the Mysterious Mima Mounds". SouthSoundMag.com. Retrieved June 16, 2025.
- ^ a b "Washington's Mysterious Mima Mounds — Pines and Vines". Pines and Vines. Retrieved June 16, 2025.
- ^ "Mima Mounds Natural Area Preserve". Washington Department of Natural Resources. Archived from the original on January 31, 2013. Retrieved December 20, 2012.
- ^ "Mima Mounds Natural Area Preserve butterfly guide" (PDF). Washington Department of Natural Resources. Retrieved June 16, 2025.
- ^ "Taylor's checkerspot". Washington Department of Fish & Wildlife. Retrieved June 16, 2025.
- ^ "Mardon skipper". Washington Department of Fish & Wildlife. Retrieved June 16, 2025.
- ^ "Mima Mounds". Washington Trails Association. Retrieved June 16, 2025.
- ^ "Mima Mounds Natural Area Preserve". Experience Olympia. Retrieved June 16, 2025.
