The Irvine Ranch Natural Landmarks comprise nearly 50,000 acres of protected open space in and around Irvine in Orange County, formed from land once part of the historic Irvine Ranch. After beginning as a cattle ranch in the 1860s and remaining in agricultural use until the late 1970s, much of the former ranch was preserved, creating a connected landscape of canyons, hills, and habitat across central and coastal Orange County. The area is important for its unusually complete stratigraphic sequence from the late Cretaceous to the present and for native communities including coastal sage scrub, chaparral, and rare Tecate cypress woodlands. Its conservation importance was recognized with National Natural Landmark status in 2006 and California Natural Landmark status in 2008.