Pinnacle Mountain (Arkansas)

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Pinnacle Mountain
Pinnacle Mountain 20171118 1632.jpg
Pinnacle Mountain as seen from Highway 300
Highest point
Elevation1,013 ft (309 m) NAVD 88[1]
Coordinates34°50′29″N 92°29′09″W / 34.841416°N 92.485815°W / 34.841416; -92.485815Coordinates: 34°50′29″N 92°29′09″W / 34.841416°N 92.485815°W / 34.841416; -92.485815[1]
Geography
Pinnacle Mountain is located in Arkansas
Pinnacle Mountain
Pinnacle Mountain
LocationPulaski County, Arkansas, U.S.
Parent rangeOuachita Mountains, U.S. Interior Highlands
Topo mapUSGS Pinnacle Mountain

Pinnacle Mountain is the second highest natural point in Pulaski County, Arkansas and main attraction of the 2,356-acre Pinnacle Mountain State Park.[2] It is located in the foothills of the Ouachita Mountains just outside of Little Rock, the capital and most populous city of Arkansas.

Geography[]

Pinnacle Mountain is located between the Big Maumelle River to the north and the Little Maumelle River to the south. Both rivers empty into the Arkansas River shortly after passing Pinnacle Mountain.

The U.S. Board on Geographic Names once defined a mountain as any landform greater than 1,000 feet of local relief and a hill as any landform less than 1,000 feet of local relief. Though Pinnacle Mountain is 1,011 feet above mean sea level, it is only approximately 761 feet of local relief. Due to broad disagreement over this naming convention, the classification system was abandoned in the early 1970s. According to the Geographic Names Information System (GNIS), Pinnacle Mountain is a summit, which is defined as "a prominent elevation rising above the surrounding level of the Earth's surface", but does not include mountains or hills, among other things.[3][4] Its proximity to the low-lying Arkansas River and steep south slopes make Pinnacle Mountain a prominent landform, observable from many areas in Pulaski County and elsewhere.

Geology[]

Pinnacle Mountain is not a volcano. Despite its resemblance to a cinder cone, Pinnacle Mountain is composed of deep-water sedimentary rock called the Jackfork Sandstone.[5] Named for Jackfork Mountain in Oklahoma, the Jackfork Sandstone at Pinnacle Mountain is an exceptionally hard quartzitic sandstone, mostly massive-bedded, fine-grained, and tan.[6]

The Jackfork Sandstone was deposited in a developing foreland basin during the early stages of the Ouachita Orogeny, the mountain-building event that formed the Ouachita Mountains.[7] The Jackfork Sandstone is a geologic deposit of turbidity currents, essentially underwater landslides. The terrane has been deeply eroded by high rates of weathering throughout the Mesozoic and Cenozoic.[8]

Hiking[]

Two routes ascend Pinnacle Mountain: the 1.5-mile West Summit Trail (designated by yellow markers), which starts at the West Summit parking off of Highway 300, and the 1.5-mile East Summit Trail (designated by red and white markers), which starts at the East Summit parking lot off of Pinnacle Valley Road.[9] The West Summit Trail tends to see considerably more foot traffic than the East Summit Trail, primarily because the East Summit Trail entails moderate scrambling (i.e., off-trail hiking incorporating the use of hands for balance and occasionally to hold the terrain). Both, however, receive a large number of visitors due to their proximity to Little Rock. The 3-mile Base Trail (designated by light green markers) loops completely around the base of Pinnacle Mountain and connects the West Summit and East Summit trailheads.[9] The 223-mile Ouachita Trail (designated by blue markers) overlaps a 0.5-mile section of the Base Trail and continues another 1.5 miles to the Pinnacle Mountain State Park Visitor Center after crossing Pinnacle Valley Road at the East Summit parking lot.[9]

See also[]

References[]

  1. ^ a b "MAUMELLE RESET". NGS data sheet. U.S. National Geodetic Survey. Retrieved 2017-10-30.
  2. ^ "Pinnacle Mountain State Park". Arkansas State Parks. Retrieved 2017-10-30.
  3. ^ "Pinnacle Mountain". Geographic Names Information System. United States Geological Survey. Retrieved 2017-11-21.
  4. ^ "Feature Class Definitions". United States Geological Survey. Retrieved 2017-11-21.
  5. ^ "Geologic Map of Arkansas" (PDF). Arkansas Geological Survey. Retrieved 2017-10-22.
  6. ^ "Stratigraphic Summary of the Arkansas River Valley and Ouachita Mountains". Arkansas Geological Survey. Archived from the original on 2018-05-29. Retrieved 2017-10-30.
  7. ^ Shanmugam, G.; Moiola, R.J. (1995). "Reinterpretation of Depositional Processes in a Classic Flysch Sequence (Pennsylvanian Jackfork Group), Ouachita Mountains, Arkansas and Oklahoma". AAPG Bulletin. 79 (5): 672–695.
  8. ^ Morris, R.C. (1974). "Sedimentary and Tectonic History of the Ouachita Mountains". Special Publications of SEPM. 22: 120–142.
  9. ^ a b c "Trails of Pinnacle Mountain State Park" (PDF). Arkansas State Parks. Retrieved 2017-10-31.
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