| Mahogany Mountain | |
|---|---|
 Leslie Gulch rock spire, Mahogany Mountain, Oregon. Photo: BLM (2008). | |
| Highest point | |
| Elevation | 6,526 ft (1,989 m) NAVD 88[1] |
| Prominence | 1,892 ft (577 m)[2] |
| Coordinates | 43°14′06″N117°15′21″W / 43.234976817°N 117.255852547°W /43.234976817; -117.255852547[1] |
| Geography | |
  Mahogany Mountain Location in Oregon Show map of Oregon Mahogany Mountain Mahogany Mountain (the United States) Show map of the United States | |
| Location | Malheur County,Oregon, U.S. |
| Parent range | Owyhee Mountains |
| Topo map | USGS McCain Creek |
| Geology | |
| Last eruption | 15.5 million years ago |
Mahogany Mountain is an ancientcalderavolcano on the border ofOregon andIdaho, inMalheur County andOwyhee County, respectively. While its early history is largely unknown, its last eruption was probably 15.5 million years ago. This eruption ejected layers ofrhyolite and producedtuff, creating formations of rock in theLeslie Gulch.
Nearby features include theOwyhee River, historically used as a fishing and camping ground for early Native Americans. The climate of the area tends to be extreme; that is, it is cold in the winter and hot in summer. Sparse vegetation is present, includingshrubs and patches ofjuniper.
A part of theBasin and Range Province, the volcano's most recent eruptive activity dates to approximately 15 million years ago (theMiocene), forming during a period of active volcanism including eruptions ofignimbrite andash. It formed around the same time asThree Fingers,Castle Peak, and three other volcanoes. Today the volcano appears gnarled due toerosion and is topped bypine forests.[3][verification needed] The caldera is narrow and shaped like a ridge, with precipitous slopes and anescarpment on the northwest flank. It consists ofrhyolitetuff andsedimentary layers.[4]
Leslie Gulch lies within the depression of the volcano. Layers of ash and tuff are evident in the formation, and leftover volcanic rocks sit in it as well.[5] The gulch features an array of rock formations and ash erupted from the volcano approximately 15.5 million years ago.[6]
The nearbyOwyhee River was utilized byNative Americans as early as 5,000 years before European habitation of the area. It served as a source of food, both for fishing and hunting, and the natives often camped along its banks.[6]
The area by the volcano features cold winters and hot summers, with only 25 centimeters (10 in) of rainfall each year.Steppe-like shrubs make up the majority of the vegetation, thoughjuniper is present in patches. There are 64 known mammalian species in the area.[7]
