Franklin Mountains (Texas)

The Franklin Mountains of Texas are a small range (23 miles long, 3 miles (4.8 km) wide) that extend from El Paso, Texas north into New Mexico. The Franklins were formed due to crustal extension related to the Cenozoic Rio Grande rift. Although the present topography of the range and adjoining basins is controlled by extension during rifting in the last 10 million years, faults within the range also record deformation during the Laramide orogeny, between 85 and 45 million years ago.

The highest peak is North Franklin Mountain at 7,192 feet (2,192 m). Much of the range is part of the Franklin Mountains State Park. The mountains are composed primarily of sedimentary rock with some igneous intrusions. Geologists refer to them as tilted-block fault mountains and in them can be found 1.25 billion-year-old Precambrian rocks, the oldest in Texas.

• View of the south end of Franklin Mountains from El Paso, showing the abrupt termination of the range, its westward dip slope and terraced bolson deposits on each side. (1908)

• View of South Franklin Mountain (aka Mount Franklin) (29 March 2009)

• North Franklin Mountains in November.