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Ouachita Mountains

Coordinates:35°10′01″N93°38′41″W/ 35.167016203°N 93.644725919°W/35.167016203; -93.644725919
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Ouachita Mountains
The Ouachita Mountains near Caney Creek, Arkansas
Highest point
PeakMount Magazine
Elevation2,753 ft (839 m)
Coordinates35°10′01″N93°38′41″W/ 35.167016203°N 93.644725919°W/35.167016203; -93.644725919
Naming
EtymologyChoctawfor "large bison"[1]or "big hunt",[1]orCaddo[2]
Geography
Level III ecoregions in the region, with the Ouachita Mountains ecoregion marked as (36) (full map)
CountryUnited States
StateArkansasandOklahoma
Parent rangeU.S. Interior Highlands
Borders onArkansas Valley (37),Mississippi Alluvial Plain (73),South Central Plains (35)

TheOuachita Mountains(/ˈwɒʃɪtɔː/), simply referred to as theOuachitas,are amountain rangein westernArkansasand southeasternOklahoma.They are formed by a thick succession of highly deformedPaleozoicstrata constituting the Ouachita Fold and Thrust Belt, one of the importantorogenic beltsofNorth America.[3]The Ouachitas continue in the subsurface to the northeast, where they make a poorly understood connection with theAppalachiansand to the southwest, where they join with theMarathon upliftarea ofWest Texas.[3]Together with theOzark Plateaus,the Ouachitas form theU.S. Interior Highlands.[4]The highest natural point isMount Magazineat 2,753 feet (839 m).[2][5]

The Ouachita Mountains is aLevel III ecoregiondesignated by theEnvironmental Protection Agency(EPA). The region has been subdivided into sixLevel IV ecoregions.[6][7]

Etymology[edit]

Louis R. Harlan claimed that "Ouachita" is composed of theChoctawwordsouacfor "bison" andchitofor "large", together meaning "country of large bison". At one time, herds ofbisoninhabited the lowland areas of the Ouachitas.[8]HistorianMuriel H. Wrightwrote that "Ouachita" is composed of theChoctawwordsowafor "hunt" andchitofor "big", together meaning "big hunt far from home".[1]According to the articleOuachitain theEncyclopedia of Oklahoma History and Culture,"Ouachita" comes from the French spelling of theCaddowordwashita,meaning "good hunting grounds".[2]

Geography[edit]

Ouachita Flora
The Ouachita National Forest during the fall
A map of the Ouachita mountains within the states of Arkansas and Oklahoma.
Topographic map of the Ouachita Mountains

The Ouachitas are a major physiographic province ofArkansasandOklahomaand are generally grouped with theArkansas River Valley.Together with theOzark Plateaus,the Ouachitas form theU.S. Interior Highlands,one of few mountainous regions between theAppalachiansandRockies.[4]

Flora[edit]

The Ouachitas are dominated by pine, oak, and hickory.[9]The shortleaf pine (Pinus echinata) and post oak (Quercus stellata) thrive in dry, nutrient-poor soil and are common in upland areas. The maple-leaf oak (Quercus acerifolia) is found at only four sites worldwide, all of which are in the Ouachitas.[9]Some native tree species, such as the eastern red-cedar (Juniperus virginiana), are colonizers of human-disturbed sites.[9]

TheOuachita National Forestcovers approximately 1.8 million acres of the Ouachitas.[10]It is one of the largest and oldest national forests in theSouthern U.S.,created through an executive order by PresidentTheodore Roosevelton December 18, 1907.[10]There are six wilderness areas within theOuachita National Forest,which are protected areas designed to minimize the impacts of human activities.[11]

Several plants areendemicto the Ouachitas, including:Agalinis nuttallii,Cardamine angustatavar.ouachitana,Carex latebracteata,Galium arkansanumvar.pubifolium,Houstonia ouachitana,Hydrophyllum brownei,Liatris compacta,Quercus acerifolia,Polymnia cossatotensis,Solidago ouachitensis,Spiranthes niklasii(near endemic, also found onCrowley's Ridge),Streptanthus maculatussubsp.obtusifolius,Streptanthus squamiformis,Valerianella palmerii,andVernonia lettermanii.[12]

Fauna[edit]

Bisonandelkonce found habitat in the Ouachita Mountains, but have since been extirpated. Today, there are large populations ofwhite-tailed deer,coyote,and other common temperate forest animals. Though elusive, hundreds ofblack bearroam the Ouachitas. Severalcryptic speciesofsalamanderare endemic to the Ouachitas and have traits that vary from one locale to another.[13]

Subranges[edit]

Athens Plateau[edit]

TheAthens PlateauorAthens Piedmont(EPA Level IV ecoregion 36a) consists of a series of low relief ridges, none exceeding 1,000 feet (300 m). It is located south of the Ouachitas and extends from to the Arkansas-Oklahoma border. The Athens Piedmont runs fromArkadelphia, Arkansasinto Oklahoma throughClark,Howard,Pike,andSeviercounties in Arkansas andMcCurtain Countyin Oklahoma. The ecoregion's low ridges and hills are widely underlain byMississippianStanley Shalein contrast to other parts of the Ouachitas.[7]Today, pine plantations are widespread; they are far more extensive than in the more rugged parts of the Arkansas Ouachitas. Pastureland and hayland also occur. Cattle and broiler chickens are important farm products.[6]

TheCaddo,Cossatot,andMissourimountains are a high, compact group of mountains composed of the weather-resistant Arkansas Novaculite. They are located primarily inMontgomeryandPolkcounties, Arkansas. The highest natural point is Raspberry Mountain at 2,358 feet (719 m). The headwaters of multiple rivers are found in this area, including theCaddo,Cossatot,andLittle Missouririvers.

TheCross Mountainsare located inPolkandSeviercounties, Arkansas andMcCurtain County, Oklahoma.The highest natural point is Whiskey Peak at 1,670 feet (510 m).

TheCrystal Mountainsare located primarily inMontgomery County, Arkansas.They are so named because of the occurrence of some of the world's finestquartz.The Crystal Mountains are generally taller than the nearby Zig Zag Mountains, achieving elevations over 1,800 feet (550 m).

Fourche Mountains[edit]

TheFourche Mountains(EPA Level IV ecoregion 36d) are a long, continuous chain of east-west mountains composed of the weather-resistantJackfork Sandstone.They extend fromPulaski County, ArkansastoAtoka County, Oklahomaand are home to several popular sites of interest, includingPinnacle Mountain State ParknearLittle Rock, Arkansas.The highest natural point isRich Mountainat 2,681 feet (817 m), which intersects the Arkansas-Oklahoma border nearMena, Arkansas.

Fourche Mountain salamander

The Fourche Mountains are the archetypal Ouachita Mountains. Forested ridges are heavily forested with oak–hickory–pine forest; intervening valleys are cut into shale. Ridges are longer, habitat continuity is greater, the lithologic mosaic is different, and the topographic orientation is more consistent than in other parts of the Ouachitas. Differences in moisture and temperature between north- and south-facing slopes significantly influence native plant communities; they are products of the prevailing topographic trend.[6]Forests on steep, north-facing slopes are moremesicthan on southern aspects; the steepest, south-facing slopes contain shallow, moisture deficient soils supporting shrubs and rocky glades or grassy woodlands.[7]Pastureland and hayland are restricted to a few broad valleys. Logging is not nearly as intensive as in the commercial pine plantations of the less rugged Athens Plateau. Nutrient, mineral, and biochemical water quality parameter concentrations are low in the surface waters of the Fourche range, butturbiditycan be higher than in other mountainous parts of the Ouachitas.[6]Although most streams stop flowing during the driest part of the summer, enduring deep pools, high quality habitat, and good water quality allow sensitive aquatic species to survive through the summer.[7]They are the only home and namesake of theFourche Mountain salamander.

The Fourche Mountains form a major watershed divide between the Arkansas River Basin to the north and the Red River Basin to the south.

TheFrontal Ouachita Mountainsare located in theArkansas River Valleyand feature a number of isolated landforms. The highest natural point isMount Magazineat 2,753 feet (839 m), which is also the highest natural point of the Ouachitas andU.S. Interior Highlands.The Frontal Ouachita Mountains are structurally quite different from the rest of the Ouachitas and are sometimes considered a separate range.

TheTrap Mountainsare located primarily inGarlandandHot Springcounties,Arkansas.The highest natural point is Trap Mountain at 1,310 feet (400 m).

TheZig Zag Mountainsare located inGarland County, Arkansas,and are home to the thermal springs ofHot Springs National Park.They are so named because of their unique chevron shape when viewed from above, the result of plunginganticlinesandsynclines.The Zig Zag Mountains are not exceptionally tall, but do reach heights over 1,400 feet (430 m).

Geology[edit]

Vertical strata in the eastern Ouachitas
Cluster of Arkansas quartz crystals from the Ouachita Mountains

The Ouachitas are formed by a thick succession of highly deformedPaleozoicstrata constituting the Ouachita Fold and Thrust Belt, which crops out for approximately 220 miles (350 km) in westernArkansasand southeasternOklahoma.[3]In a general sense, the Ouachitas are considered an anticlinorium because the oldest known rocks are located towards the center of the outcrop area.[14]The Ouachitas continue in the subsurface to theBlack Warrior BasinofAlabamaandMississippiwhere they plunge towards theAppalachian Mountains.[15]To the southwest, the Ouachitas join with the Marathon area of westTexaswhere rocks of the Ouachita Fold and Thrust Belt are briefly exposed.[3]

Unlike many ranges in theUnited States,the Ouachitas are mostly east-west trending. They are unique becausemetamorphismandvolcanism,features that are common in orogenic belts, are notably absent (with the exception of some low-grademetamorphism). Due to the high degree of folding and faulting, the Ouachitas are clustered into distinct subranges, with ridges separated by relatively broad valleys.

The Ouachitas are known for some of the world's finestquartz,especially aroundMount Ida, Arkansas,the quartz capital of the world.[16]The quartz formed after theOuachita Orogenywhen fractures in rocks filled with silica-saturated fluids and, over millions of years, precipitated crystals up to several feet in length. The Ouachitas are also known fornovaculite,a variety ofchertthat has undergone low-grademetamorphism;particular grades found only inArkansasare used for makingwhetstones.

History[edit]

CambrianthroughMississippianstrata of the Ouachitas were deposited in a narrow, two-sided basin called the Ouachita Trough, which formed as part of aCambrianfailed rift system.[3][17]SucceedingPennsylvanianstrata of the Ouachitas were deposited in aforeland basinduring the early stages of theOuachita Orogeny.[18]Subduction of theSouth American Platebeneath theNorth American Plateresulted in this mountain-building event.[19]Compressional forces caused the crust to buckle, producing complex folds at all scale levels and several overturned sequences.[14]The area of greatest deformation occurred in the Benton-Broken Bow Uplift, which extends fromBenton, ArkansastoBroken Bow, Oklahoma.[3]The total height of the Ouachitas is not known, though they may have exceeded 10,000 feet (3,000 m) (based loosely on geologic cross-sections).[14]The terrain has been deeply eroded since the latePaleozoic.[3]

Stratigraphy[edit]

The Ouachitas are composed ofCambrianthroughPennsylvaniansedimentary rocks.The Collier Shale, located at the core of the Benton-Broken Bow Uplift, is the oldest exposed formation of the Ouachitas. TheAtoka Formation,which was deposited much later during thePennsylvanian,has the largest areal extent of any of thePaleozoicformations inArkansas.[14] The geologic formations of the Ouachitas are as follows (in order of ascending age).

Formation Period Approximate thickness
Collier Shale LateCambrianand EarlyOrdovician 1,000 feet (300 m)
Crystal Mountain Sandstone Early Ordovician 850 feet (260 m)
Mazarn Shale Early Ordovician 2,500 feet (760 m)
Blakely Sandstone Middle Ordovician 700 feet (210 m)
Womble Shale Middle Ordovician 1,200 feet (370 m)
Bigfork Chert Middle and Late Ordovician 750 feet (230 m)
Polk Creek Shale Late Ordovician 225 feet (69 m)
Blaylock Sandstone Silurian 1,200 feet (370 m)
Missouri Mountain Shale Silurian 300 feet (91 m)
Arkansas Novaculite Devonianand EarlyMississippian 900 feet (270 m)
Stanley Shale Mississippian 10,000 feet (3,000 m)
Jackfork Sandstone EarlyPennsylvanian 6,000 feet (1,800 m)
Johns Valley Shale Early Pennsylvanian 1,500 feet (460 m)
Atoka Formation Early and Middle Pennsylvanian 25,000 feet (7,600 m)
Hartshorne Sandstone Middle Pennsylvanian 300 feet (91 m)
McAlester Formation Middle Pennsylvanian 2,300 feet (700 m)
Savanna Formation Middle Pennsylvanian 1,600 feet (490 m)
Boggy Formation Middle Pennsylvanian 1,100 feet (340 m)

History[edit]

The mountains were home to theOuachita tribe,for which they were named. Later French explorers translated the name to its present spelling. The first recorded exploration was in 1541 byHernando de Soto.Later, in 1804,President JeffersonsentWilliam Dunbarand Dr. George Hunter to the area after theLouisiana Purchase.Hot Springs National Parkbecame one of the nation's first parks in 1832. TheBattle of Devil's Backbonewas fought here at the ridge of the same name in 1863. In August 1990, theU.S. Forest Servicediscontinuedclearcuttingas the primary tool for harvesting and regenerating short leaf, pine and hardwood forests in the Ouachita National Forest.

Tourism[edit]

The Ouachita Mountains contain theOuachita National Forest,Hot Springs National ParkandLake Ouachita,as well as numerous state parks and scenic byways mostly throughout Arkansas. They also contain theOuachita National Recreation Trail,a 223-mile-long (359 km) hiking trail through the heart of the mountains. The trail runs from Talimena State Park in Oklahoma toPinnacle Mountain State ParknearLittle Rock.It is a well maintained, premier trail for hikers, backpackers, and mountain bikers (for only selected parts of the trail).

TheTalimena Scenic Drivebegins atMena,and traverses 54 miles (87 km) of Winding Stair and Rich Mountains, long narrow east-west ridges which extend into Oklahoma.Rich Mountainreaches an elevation of 2,681 feet (817 m) in Arkansas near the Oklahoma border. The two lane winding road is similar in routing, construction, and scenery to theBlue Ridge Parkwayof theAppalachian Mountains.[20]

Sites of interest[edit]

TheSouth Fourche La Fave River,Ouachita Mountains, Arkansas

References[edit]

  1. ^abcWright, M.H. (1929). "Some Geographic Names of French Origin in Oklahoma".Chronicles of Oklahoma.7(2): 188–193.
  2. ^abcCole, S.R.; Marston, R.A. (2009).Encyclopedia of Oklahoma History and Culture.Oklahoma Historical Society.{{cite encyclopedia}}:Missing or empty|title=(help)
  3. ^abcdefgMorris, R.C. (1974). "Sedimentary and Tectonic History of the Ouachita Mountains".Special Publications of SEPM.22:120–142.
  4. ^ab"A Tapestry of Time and Terrain".U.S. Geological Survey.RetrievedOctober 13,2007.
  5. ^"MAG".NGS Data Sheet.National Geodetic Survey,National Oceanic and Atmospheric Administration,United States Department of Commerce.RetrievedDecember 16,2008.
  6. ^abcdPublic DomainThis article incorporatespublic domain materialfromWoods, A.J.; Foti, T.L.; Chapman, S.S.; Omernik, J.M.; et al.Ecoregions of Arkansas(PDF).United States Geological Survey.(color poster with map, descriptive text, summary tables, and photographs).
  7. ^abcdPublic DomainThis article incorporatespublic domain materialfromWoods, A.J.; Omernik, J.M.; Butler, D.R.; Ford, J.G.; et al.Ecoregions of Oklahoma(PDF).United States Geological Survey.RetrievedOctober 14,2020.(color poster with map, descriptive text, summary tables, and photographs).
  8. ^Harlan, L.R. (1834). "Notice of Fossil Bones Found in the Tertiary Formation of the State of Louisiana".Transactions of the American Philosophical Society.4:397–403.doi:10.2307/1004838.JSTOR1004838.
  9. ^abc"Trees".Central Arkansas Library System.RetrievedNovember 28,2017.
  10. ^ab"Ouachita National Forest".Central Arkansas Library System.RetrievedNovember 28,2017.
  11. ^"Wilderness Areas (Ouachita National Forest)"(PDF).U.S. Forest Service.RetrievedDecember 2,2017.
  12. ^Zollner, Douglas; MacRoberts, Michael H.; MacRoberts, Barbara R.; Ladd, Douglas (2005). "Endemic Vascular Plants of the Interior Highlands, U.s.a".SIDA, Contributions to Botany.21(3): 1781–1791.ISSN0036-1488.JSTOR41968453.
  13. ^Shepard, Donald B.; Irwin, Kelly J.; Burbrink, Frank T. (December 2011). "Morphological Differentiation in Ouachita Mountain Endemic Salamanders".Herpetologica.67(4): 355–368.doi:10.1655/HERPETOLOGICA-D-11-00023.1.ISSN0018-0831.S2CID84672236.
  14. ^abcd"Stratigraphic Summary of the Arkansas River Valley and Ouachita Mountains".Arkansas Geological Survey. Archived fromthe originalon May 29, 2018.RetrievedOctober 26,2017.
  15. ^Mellen, F.F. (1947). "Black Warrior Basin, Alabama and Mississippi".AAPG Bulletin.31(10): 1801–1816.doi:10.1306/3d933a55-16b1-11d7-8645000102c1865d.
  16. ^"Quartz Crystals".Arkansas Department of Parks & Tourism.RetrievedNovember 25,2017.
  17. ^Lowe, D.R. (1985). "Ouachita Trough: Part of a Cambrian Failed Rift System".Geology.13(11): 790–793.Bibcode:1985Geo....13..790L.doi:10.1130/0091-7613(1985)13<790:otpoac>2.0.co;2.
  18. ^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.doi:10.1306/8d2b1b6a-171e-11d7-8645000102c1865d.
  19. ^Hatcher, R.D. Jr.; Thomas, W.A.; Viele, G.W., eds. (1989).The Appalachian-Ouachita Orogen in the United States (Geology of North America).Colorado: Geological Society of America.
  20. ^http://www.trais.com/tcatalog_trail.aspx?trailid=XFA101-040ArchivedJuly 17, 2011, at theWayback Machine,accessed 11 Mar 2011

Further reading[edit]

External links[edit]

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