Located in north central Illinois near Pecatonica, Wilson Prairie is a dry gravel hill prairie of about 20 acres. It has been evaluated as a category II site with a state-endangered species, the large-flowered beard tongue (Penstemon grandiflorus), and an early spring bloom of pasque flowers (Anemone patens). The dedication describes the geological characteristics of the prairie as follows: The site is characterized by a ridge crossing from the northeast to the southwest corner, sloping downward away from the ridge gradually to the southeast, and more steeply to the northwest where the site reaches Sumner Creek. The rise from the creek to the highest point of the ridge on site is about 70 feet. Underlying bedrock is brownish or brownish-gray dolomite of the Galena and Plattville Groups. (Berg et al. 1984). Frye et al. (1969) show this site within the Pecatonica Lobe of the Altonian Argyle till. More recently, though, Berg et al. (1984) indicate Illinoian as the most recent glaciation, and a shallow glacial deposit of Ogle till (Glassford Formation). Soils along the ridge are Sogn silt loam (504E), which is associated with "native prairie..." in Winnebago County (USDA 1976). Along either side of the ridge are Rockton and Dodgeville soils (566C2, 566D2). Sources: Proposal to Dedicate Wilson Prairie, Winnebago County, IL as an Illinois Nature Preserve; prepared for James H. Wilson, January, 1991, by John Alesandrini and Gillian Moreland. Berg, R.C., J.P. Kempton and A.N. Stecyk. 1984. Geology for Planning in Boone and Winnebago Counties. IL Geol. Survey Circ. 531. 69p +maps. Frye, J.C., H.D. Glass, J.P. Kempton and H.B. Willman. 1969. Glacial Tills of Northwestern Illinois. IL Geol. Survey Circ. 437. 45p. U.S. Department of Agriculture. 1976. Soil Survey of Winnebago and Boone Counties, Illinois. IL Agric. Exper. Station Soil Report No. 107. 279p +maps