The Sentinel Plain is an extensive northwest–southeast trending

plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...

south of the

Gila River Valley The Gila River Valley is a multi-sectioned valley of the Gila River, located primarily in Arizona. The Gila River forms in western New Mexico and flows west across southeastern, south-central, and southwestern Arizona; it changes directions as i ...

in southwestern

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

, USA. It is centered on the community of

Sentinel, Arizona Sentinel is an unincorporated community in Maricopa County, Arizona, United States. It has an estimated elevation of above sea level. The train station served the US Army training camps: Camp Horn and Camp Hyder during World War II Wo ...

located on

Interstate 8 Interstate 8 (I-8) is an Interstate Highway in the southwestern United States. It runs from the southern edge of Mission Bay at Sunset Cliffs Boulevard in San Diego, California, almost at the Pacific Ocean, to the junction with I-10, ...

, approximately west of

Gila Bend Gila Bend (; O'odham: Hila Wi:n), founded in 1872, is a town in Maricopa County, Arizona, United States. The town is named for an approximately 90-degree bend in the Gila River, which is near the community's current location. As of the 2020 cen ...

. The Sentinel Plain is about long and on the north-northwest, it borders the

Hyder Valley The Hyder Valley is a 20-mile (32 km) long valley section of the Gila River Valley west of Hyder on the Gila River. The valley is located north of Gila River in southwest Arizona in the northwestern Sonoran Desert. The Park Valley, which cro ...

and the farming community of Hyder on the

Gila River The Gila River (; O'odham ima Keli Akimel or simply Akimel, Quechan: Haa Siʼil, Maricopa language: Xiil) is a tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of n ...

. To the northeast is

Painted Rock Reservoir The Painted Rock Dam is an earthfill embankment dam located west of Gila Bend, Arizona. It is primarily used for flood control purposes. Description The Painted Rock Dam was constructed during a 3-year period from 1957–1960 by the United Stat ...

and the Painted Rock Mountains. The south and southwest of the Sentinel Plain is bordered by the Crater Range; the east and southeast is bordered by the White Hills, and the Saucedo Mountains. Midway Wash drains into the center of the plain southeast-northwesterly, but disappears into the ground about 10 miles southeast from the Gila River. The west and southwestern border of the plain contains the northwest-flowing

Tenmile Wash Tenmile Wash is an ephemeral wash and watercourse about long in the northern Sonoran Desert of south-central Arizona. It forms the eastern drainage of a two drainage system of dry washes into the Gila River Valley; both flow northwesterly, and the ...

-(which also succumbs to ground disappearance, but adjacent to the Gila), and the northwest trending Crater Range.

See also