Tierra Redonda Mountain is a 2,051-foot summit in northwestern San Luis Obispo County near Lake Nacimiento and the Santa Lucia Range. Though modest in height, it is notable for its distinctive setting across the Nacimiento River from the main ridge, its mix of chaparral, blue oak woodland, grassland, and unusual sand dunes, and its protected 320-acre Bureau of Land Management parcel. The area has been designated an Area of Critical Environmental Concern because of its sensitive and threatened plant species and rich paleontological resources, including rare Chorizanthe populations and fossil-bearing outcrops of the Vaqueros Formation. It also holds a small local tradition as an early pioneer picnic destination.