|Peak||North Franklin Peak|
|Elevation||7,192 ft (2,192 m)|
|States||Texas and New Mexico|
|Age of rock||Cretaceous|
|Type of rock||Sedimentary, Igneous|
The Franklin Mountains of Texas (previously known as Las Sierras de los Mansos) 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 Peak 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)
Franklin Mountains with Northwest El Paso in the background
- Miles, Robert W. (2010-06-12). "Franklin Mountains". tshaonline.org. Retrieved 2020-03-29.
- Van Hise, C. R.; Leith, C. K. (1909). Pre-Cambrian Geology of North America. United States Geological Survey, Bulletin. 360. pp. 746–748. doi:10.3133/b360. OCLC 271845.
- "Franklin Mountains State Park : Interpretive Guide" (PDF). Texas State Parks. 2019. Precambrian rocks can be seen in the Tom Mays unit of the Franklin Mountains park.
- Brooks, A. H. (1904). "The Geological Society of Washington". Science. NS. 19 (490): 794–796. doi:10.1126/science.19.490.794.
- Richardson, G. B. (1909). El Paso folio, Texas. United States Geological Survey, Folios of the Geologic Atlas. No. 166. Figure 10. doi:10.3133/gf166. OCLC 2514134.
|Wikimedia Commons has media related to Franklin Mountains (Texas).|