Big Rock, a twelve-foot-high, 103-ton granite boulder in what became Tawawa Park, arrived about 15,000 years ago when a mile-thick sheet of glacial ice carried it southwest into Ohio from its native source to the northeast. According to geologist and Sidney native Albert Binkley Dickas, its mineral makeup matches a 985-million-year-old granite outcrop exposed between Ottawa and Sudbury in southeastern Canada. During the most recent ice age, glacial meltwater entered fractures in the granite, froze, expanded, and broke off fragments that moving ice carried 700 miles until warming climate melted the glacier and left Big Rock behind. The boulder, along the Ward Trail at one end of Aschenbach Grove, has long been a gathering place for families and friends, a favorite climbing spot for children, and a setting for marriage proposals. Although no one knows when it acquired the name Big Rock, the name was firmly established by 1876, when a Sidney Journal account reported that six stonecutters carved the outline of the U. S. National Shield on its upper face, along with their names, and the name of William Binkley on its north face.