Steens Mountain is in the southeastern part of the U.S. state of Oregon, and is a large fault-block mountain. Located in Harney County, it stretches some north to south, and rises from the west side the Alvord Desert at elevation of about to a summit elevation of . Steens Mountain is not part of a mountain range but is properly a single mountain, the largest of Oregon's fault-block mountains. The Steens Mountain Wilderness encompasses of Steens Mountain. of the Wilderness are protected from grazing and free of cattle. History The mountain was called the "Snowy Mountains" by John Work, one of the fur traders who were the first Europeans in the area. It was renamed in 1860 for United States Army Major Enoch Steen, who fought and drove members of the Paiute tribe off the mountain. American Indians used the Steens Mountain, particularly Big Indian Gorge. Geology The east face of Steens Mountain is composed mainly of basalts stacked one upon another. Lava flows several hundreds of feet thick inundated the region between 17 and 14 million years ago. Chemical data from magma deposits from the area reveal three distinct stages of volcanism. Layers of clay and volcanic dust show over forty lava flows on Steens Mountain. Most lava layers reach to thick or more in some areas. As the surface cracked, peaks and valleys were formed. Erosion and landfalls continue to modify the faces of the cliffs along the mountain. The sediment bedding is roughly horizontal, evidence to the absence of compressional forces. The white sediments consist primarily of stratified acidic tuffs. While rain hasn't been a main contributor to erosion, ice and snow melt are the main sources of erosion on Steens Mountain. Flora and fauna Vegetation in the Steens Mountain Wilderness varies greatly according to elevation. Common plants include sagebrush, juniper, various species of bunchgrass, mountain mahogany, aspen, mountain meadow knotweed, and false hellebore. Other vegetation endemic to Steens Mountain includes Steens paintbrush (Castilleja pilosa var. steenensis), moss gentian (Gentiana fremontii), Steens Mountain penstemon (Penstemon davidsonii var. praeteritus), Steens Mountain thistle (Cirsium peckii), a dwarf blue lupine, and Cusick's buckwheat (Eriogonum cusickii). Steens Mountain is distinctive in its absence of conifers, especially Ponderosa Pine and Douglas Fir, at elevations in which they would normally be found – from above sea level. Although other mountains of the Great Basin also lack conifers, Steens Mountain is the largest mountain