Ahtanum Ridge is a long

anticline In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...

ridge A ridge or a mountain ridge is a geographical feature consisting of a chain of mountains or hills that form a continuous elevated crest for an extended distance. The sides of the ridge slope away from the narrow top on either side. The line ...

Yakima County Yakima County is a county in the U.S. state of Washington. As of the 2020 census, its population was 256,728. The county seat and largest city is Yakima. The county was formed out of Ferguson County in January 1865 and is named for the Yakama t ...

in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

. It is located just south of the city of

Yakima Yakima ( or ) is a city in and the county seat of Yakima County, Washington, and the state's 11th-largest city by population. As of the 2020 census, the city had a total population of 96,968 and a metropolitan population of 256,728. The uninco ...

, and much of its length is at the northern edge of the

Yakama Indian Reservation The Yakama Indian Reservation (spelled Yakima until 1994) is a Native American reservation in Washington state of the federally recognized tribe known as the Confederated Tribes and Bands of the Yakama Nation. The tribe is made up of Klikitat, ...

. Ahtanum Ridge is part of the

Yakima Fold Belt The Yakima Fold Belt of south-central Washington, also called the Yakima fold-and-thrust belt, is an area of topographical folds (or wrinkles) raised by tectonic compression. It is a structural-tectonic sub province of the western Columbia Plat ...

of east-tending long ridges formed by the folding of

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

Columbia River basalt flows.Complete Report for Saddle Mountains structures
, USGS Earthquake Hazards Program Ahtanum Ridge separates Yakima Valley on the south from Ahtanum Valley on the north. At the eastern end of Ahtanum Ridge the

Yakima River The Yakima River is a tributary of the Columbia River in south central and eastern Washington state, named for the indigenous Yakama people. Lewis and Clark mention in their journals that the Chin-nâm pam (or the Lower Snake River Chamnapam Nat ...

flows through Union Gap. The ridge continues east of

Union Gap Union Gap is a city in Yakima County, Washington, United States. As of the 2020 census, the city population was 6,568. Union Gap has become the retail hub for the entire Yakima Valley as a result of Valley Mall and other thriving businesses be ...

as the

Rattlesnake Hills The Rattlesnake Hills, also known as Rattlesnake Ridge, is a 16-mile (26 km) long anticline mountain ridge in Yakima County and Benton County in the U.S. state of Washington. It should not be confused with the much smaller Rattlesnake Ridge ...

References

External links

* Ridges of Washington (state) Ridges of Yakima County, Washington {{YakimaCountyWA-geo-stub