The Central Colorado volcanic field is a broad volcanic region in the southern Rocky Mountains, centered on the Thirtynine Mile volcanic area in Park County and stretching across much of central Colorado. Formed by eruptions between about 38 and 29 million years ago, it included at least ten volcanic centers or calderas that spread volcanic rocks over about 22,000 square kilometers. Its Wall Mountain Tuff supplied the stone later quarried near Castle Rock for Front Range construction. The field also became important for mining, especially at Cripple Creek, where a major gold rush began in 1890. Its lasting significance lies in how it shaped the region’s landscape, building stone industry, and mining economy.