Mima Mounds Natural Area Preserve, Natural prairie preserve in Thurston County, Washington, United States
Mima Mounds Natural Area Preserve is a 756-acre protected prairie in southwest Thurston County, Washington, between Capitol State Forest and Littlerock. It holds roughly 8 to 10 dome-shaped mounds per acre, each 1 to 7 feet (0.3 to 2.1 m) high and 7 to 40 feet (2.1 to 12.2 m) across, set on an outwash plain of the Vashon Glacier. The mounds are built of andesite cobble, gravel, sand and silt, with grass, moss and wildflowers on top and a few trees.
The site earned National Natural Landmark status in 1966, recognizing its unusual geological formations and ecological value. This designation helped protect the prairie from development and established it as a place worthy of scientific study and conservation.
The Department of Natural Resources conducts prescribed burns to maintain the native prairie ecosystem, continuing traditional land management practices of indigenous peoples.
A paved path of about half a mile runs from the entrance with good accessibility, while additional gravel trails offer more exploration options. An observation platform near the entrance helps you understand the overall layout of the mounds and plan your walk.
In spring, camas flowers bloom between the mounds, turning the grassland blue and purple. On clear days, views extend to distant snow-capped peaks of Mount Rainier and Mount St. Helens on the horizon.
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