page_title: Warner Valley
section_title: Geology
hierarchical_section_title: Warner Valley / Geology
caption_attribution_description: Hart Mountain in southeastern Oregon
context_page_description: The Warner Valley is a valley in south-central Oregon in the United States. It is a remote valley at the northwestern corner of North America's Basin and Range Province. The valley is home to a chain of lakes and wetlands known as the Warner Lakes. Native Americans were present in the Warner Valley for thousands of years before European explorers arrived in the 19th century. It is the site of Fort Warner, built by the United States Army in 1867. The fort was used as a supply depot and administrative headquarters during a protracted Army campaign against Northern Paiute bands in eastern Oregon and northern California. Today, livestock ranching is the main commercial activity in the valley. The Warner Valley offers a number of recreational opportunities including hunting, fishing, bird watching, and wildlife viewing.
context_section_description: The country to the north and east of the Warner Valley is a high volcanic plateau which has undergone considerable erosion.  The Warner Valley was probably a similar high plateau before massive faulting dropped the valley floor and uplifted the land around it, forming high valley walls.  The Warner Lakes formed in the valley bottom after the faulting stopped.
  The Warner Valley is bounded by high escarpment walls on the east and west.  The main line of perpendicular displacement is along the foot of the cliffs to the east of the Warner Lakes.  This scarp feature is known as Hart Mountain.  The main cliff face of Hart Mountain towers 3,600 feet (1,100 m) above the valley floor. It runs the length of the valley, eventually being lost in a series of smaller fault scarps at the north end of the valley.  These smaller scarps generally run from the east side of the valley to the northwest.  The south end of the valley is more complex.  In that area, the valley floor is bounded on three sides by perpendicular cliffs from 1,500 to 2,000 feet (460 to 610 m) high, the result of numerous fault events.  These cliffs expose hundreds of feet of Miocene and Oligocene lava flows and ignimbrites, which include Steens basalt and various andesite, trachyandesite, and tuff flows.  The mountain mass forming the western border of the South Warner Valley is a steep fault scarp.  This cliff face rises over 2,000 feet (610 m) above the valley floor.
  Warner Valley is an alluvial basin containing numerous lakes, remnants of a single great lake that covered the valley floor up to a depth of 200 feet (61 m) during the Pleistocene epoch.  Today, steep cliffs rise above a chain of endorheic lakes.
caption: View of the Warner Valley looking west from Hart Mountain
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