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Hager Mountain
Hager Mountain is a volcanic peak in Oregon in the northwest corner of the basin and range topography of the Great Basin in the United States. The mountain is located south of the small unincorporated community of Silver Lake in south-central Oregon, and it is within the Fremont–Winema National Forest. On the summit, there is a fire lookout operated during the summer and fall by the United States Forest Service. The mountain has several hiking trails that lead to the lookout station.
== Geography and geology ==
Hager Mountain is located on the edge of Oregon's high desert in the northwest corner of the basin and range country of the western United States. The mountain is in Lake County, approximately south of the small unincorporated community of Silver Lake. The summit of Hager Mountain is above sea level. The mountain's topographic prominence is .〔〔
Hager Mountain is a large silicic lava dome structure that was formed approximately 5.9 million years ago. The mountain's primary rock is from the Hayes Butte Basalt flows. The eruptions that produced these flows came from a fault zone running southeast–northwest between Hager Mountain and Hayes Butte. The eruptions that created Hager Mountain released lava that flowed down the slopes of the volcanic dome onto plains around the mountain. The Hayes Butte Basalt overlays the ''Fort Rock Formation'' and earlier ''Picture Rock Basalt'' layers. All of these lava flows occurred during the Pliocene epoch. The Hayes Butte Basalt flows that form Hager occurred near the end of that epoch.〔Heiken, G. H., R. V. Fisher, and N. V. Peterson, ("A Field Trip to the Maar Volcanoes of the Fort Rock – Christmas Lake Valley Basin, Oregon" ), ''Geological Survey Circular 838, Guides to Some Volcanic Terrances in Washington, Idaho, Oregon, and Northern California'', United States Geological Survey, United States Department of Interior, Reston, Virginia, 1981 (updated 28 March 2006), mile 56.0.〕〔("Geothermal Significance of Rhyolite Age Progression in Oregon" ), Geological Survey Research 1975, United States Geological Survey professional paper 975, United States Geological Survey, United States Department of Interior, Reston, Virginia, 1981 (updated 28 March 2006), p. 32.〕〔Hampton, Eugene R., (''Geologic Factors That Control the Occurrence and Availability of Ground Water in the Fort Rock Basin: Lake County, Oregon'' ) (PDF), United States Geological Survey Professional Paper 383-B, United States Geological Survey (in cooperation with the Oregon State Engineer), United States Department of Interior, United States Printing Office, Washington, District of Columbia, 1964, p. B-11.〕〔Orr, William N. and Elizabeth L. Orr, (''Geology of the Pacific Northwest'' ) (Second Edition), Waveland Press, Long Grove, Illinois, 2002, p. 222.〕
When exposed on the surface, Hayes Butte Basalt generally weathers into a thin and rocky soil. Today, Hager Mountain's soil is a loose, unconsolidated mix of fine alluvial particles, gravel, and a variety of larger rock fragments. Common surface rocks include basalt, andesite, pumice, and obsidian.〔〔
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