Natural History

The Openlands Lakeshore Preserve, located in Fort Sheridan, lies on part of the Highland Park moraine, which formed as the final glacier retreated from northern Illinois about 10,000 years ago. Geologists characterize Fort Sheridan as being within the Lake Border Moraines Bluff Coast, a hilly area that extends from the town of North Chicago at the north end to Winnetka at the south, where the land flattens out again and remains relatively even through Wilmette, Evanston, and on into Chicago.

The glacial action resulted in a pleasing topography in this area, characterized by steep ravines and high bluffs along the lakefront. Part of the attractiveness of the North Shore suburbs comes from the relief provided by the hills and valleys, all products of geological forces. “Ravines are among the Bluff Coast’s most characteristic features,” writes geologist Raymond Wiggers in Geology Underfoot in Illinois. “Their precipitous gullies have been carved by youthful streams that are doing their best to cut through the high ground.”

According to Wiggers, more than thirty such ravines are located along the Illinois lakeshore—six within Fort Sheridan. The three main ravines at the Openlands Lakeshore Preserve are named Bartlett, Van Horne, and Schenck.

Fort_Sheridan_1904_Plan Credit Library of Congress_small.jpg
A map of the natural ravines near the Lakeshore Preserve (1904), Bartlett Ravine is depicted, top-right. Photo: Library of Congress

Because lake bluff terrain was unusual in Illinois, so were the natural communities that developed there—the land was forested with oaks on the ridges and sugar maples and basswood in the ravines. “[The ravines] cut the bluff perpendicular to the lake and provide a microclimate suitable for certain northern plants not otherwise found here,” writes Joel Greenberg in A Natural History of the Chicago Region. Paper birch and juniper are among the plants found at Fort Sheridan that tend to be more typical of Wisconsin and northern Michigan.

Fort Sheridan openlands

Recent History

Between 1888 and 1993, Fort Sheridan served as a U.S. Army post. Motivated by the social unrest and labor strikes of 1877 and the Haymarket Riot in 1886, the Commercial Club of Chicago, a group of wealthy businessmen, supported the use of the nation’s army as a regional police force to protect property and quell worker uprisings—a plan backed by Philip H. Sheridan, a Civil War hero and commanding general.

The organization purchased the land in 1887 and donated it to the federal government with the stipulation that the gift would be used to create a military garrison near the city. Construction began at what was initially called Camp Highwood in the spring of 1888. Shortly thereafter, President Grover Cleveland named the post in honor of General Sheridan. (Fort Sheridan troops responded to the Pullman strikes in 1894, the only time they were called upon to suppress labor unrest.)

Fort Sheridan became a mobilization, training and administrative center during the Spanish-American War and continued to serve this purpose through World War II. Many officers who would go on to become famous, including General George Patton and Jonathan Wainright, were stationed there. The 174th Military Police Battalion of the Leavenworth, Kansas, National Guard was stationed there in 1950. Additionally, from 1953 to 1973, Fort Sheridan was the Cold War base for servicing and supplying all NIKE anti-missile systems in the upper Midwest. After 1973 the post again housed administrative and logistics support services.


Fort Sheridan was among the military bases scheduled for closure under the Base Realignment and Closure (BRAC) Act of 1989 and closed in 1993. By 1995, Fort Sheridan’s 714 acres were dispersed as follows:

  • The U.S. Army retained 114 acres, which continue to serve as an Army Reserve base.
  • The U.S. Navy purchased 185 acres from the Army for use as military housing and offices; the natural features of the Openlands Lakeshore Preserve are located on this property.
  • The town of Fort Sheridan was created on 125 acres that were sold for development. There were ninety-four buildings, including sixty-four designed by the Chicago architectural firm of Holabird & Roche, built at Fort Sheridan between 1889 and 1910. Made of bricks molded and fired on-site using clay mined from the lakefront bluffs, these structures comprised troop barracks and officers’ quarters. Today, the buildings make up a 110-acre historic district that was placed on the National Register of Historic Places in 1980 and designated a National Historic Landmark in 1984.
  • Of the remaining property, 259 acres were transferred to the Lake County Forest Preserve District at no cost, including 60 acres that fell within the National Historic Landmark District

As early as the 1980’s, Openlands advocated for protecting open space at Fort Sheridan should the Fort eventually close. Once the Fort was decommissioned, Openlands played an important role in the Federal property transfer of 260 acres to the Lake County Forest Preserve District. However, there remained substantial unprotected acres of ravines, bluffs, and lakeshore on the south end of the base. At the time, no other agency or organization was able or willing to take these lands. In 2006 the phased transfer of land from the Navy to Openlands began and by 2010 Openlands acquired almost 77 acres, thus making us permanent landowners for the first time in the organization’s history. Shortly after this acquisition, construction began of onsite amenities meant to enhance visitor experiences such as ADA-accessible trails and scenic overlooks. September 2011 marked the Preserve’s grand opening and serves as a reminder of Openlands’ commitment to connecting people with nature. Openlands has since been actively restoring and providing stewardship to the Preserve’s rare natural areas.

For more information, please contact lakeshorepreserve@Openlands.org.