Modoc National Forest in northeastern California spans 1,654,392 acres and was established in 1904 as the Modoc Forest Reserve, named for the Modoc people whose traditional territory included the region. Its landscape was formed by immense lava flows over the last 500,000 years, creating a strongly volcanic terrain. The Warner Mountains rise in the eastern part, and the South Warner Wilderness lies within the forest. Plant communities vary with elevation and moisture, from brushy foothills to higher forests of pine, fir, cedar, and aspen. About 43,400 acres are old growth forest. Federal administration shifted to the U.S. Forest Service in 1905, and the forest expanded in 1908.