Gardeau Overlook takes its name from the Seneca word Gah-Da-Hoh, meaning "bank in front." More than 100,000 years ago, during a warming period between glaciers, the Genesee River eroded this valley and created a new course, and when the great ice sheets returned they left gentler slopes and desirable farmland; later wanderings of the river cut a cliff face into the slope, forming the "bank in front." The flat bottomland below was used by Native Americans thousands of years before the Seneca. Mary Jemison, known as the White Woman of the Genesee, lived here for more than 50 years after being captured as a teenager during the French and Indian War and adopted by a Seneca family. During the Revolutionary War, she brought her family to this valley to escape raids during the Sullivan Campaign. At the Treaty of Big Tree in 1797, she received 17,927 acres called the Gardeau Reservation. She remained there until 1831, then moved to the Buffalo Creek Reservation after the deaths of her sons, and stayed there until her death in 1833. The Gardeau Valley, once home to many farming families, was later acquired as park land where water could be stored behind the future dam at Mount Morris, and when the dam is full the valley fills with water above the treetops.