Mima Mounds National Natural Landmark, Washington - U.S. National Natural Landmarks on Waymarking.com

Copied from the website: http://www.nature.nps.gov/nnl/Registry/USA_Map/States/Washington/NNL/MM/index.cfm IN BRIEF One and one-half miles west of Little Rock in Thurston County. Prairie containing unusual soil pimples of black silt-gravel ranging in height from barely perceptible to a maximum of seven feet. Owner: State DESIGNATION DATE May 1966 <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Copied from another website: Copied from website: http://wdfw.wa.gov/wlm/diversty/soc/status/prairie/draft_prairie_species.pdf Mima Mounds Natural Area Preserve. Mima Mounds NAP west of Littlerock is a 445 ac preserve established in 1975 to preserve an undisturbed example of mounded prairie and the rare Roemer’s fescue/white-topped aster community (DNR 1997). Mima mounds. Mima mounds are a distinctive feature of some south Puget Sound prairies. These low, regular, rounded mounds average perhaps 6-8 feet in height and 35-50 ft in diameter, and have a density of about 8-10/ac (Washburn 1988, Kruckberg 1991). The mounds contain a bi-convex lens of fine dark soil with a high organic matter content (Mielke 1977). The mounds occur where a layer of fine loose material exists over a harder layer of rock or compacted clay or gravel. Similar mounds, which may or may not be of similar origin, occur on other grasslands in various locations in North America and on other continents. The origins of these mounds have been debated for over 100 years. (pg 23) Dalquest and Scheffer (1942) first hypothesized that the activity of pocket gophers was the force responsible for the creation of Mima mounds. Basically, gophers push material toward the center of the mound as they dig outward in their territory which is located in the same place year after year (Cox and Allen 1987, Cox and Hunt 1990). Other hypotheses include various geologic and geofluvial processes (Washburn 1988, Berg 1989). Mima mounds co-occur with burrowing rodents in North America, South America, and Africa; Reichman and Seabloom (2002) consider the burrowing mammal hypothesis for their formation to be the simplest explanation. The gopher hypothesis has been accepted by many ecologists, but no convincing evidence has been found for it, or any other hypothesis, to be widely accepted.

Predominate Feature: Mulitple mounds of earth over a large area Parking/Access Location: N 46° 54.313 W 123° 02.855 Ownership: State Terrain Rating: Admission Charged: no Landmark's Website: [Web Link]

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