The Boston Mountains is a Level III ecoregion designated by the Environmental Protection Agency (EPA) in the U.S. states of Arkansas and Oklahoma. Part of the Ozarks, the Boston Mountains are a deeply dissected plateau. The ecoregion is steeper than the adjacent Springfield Plateau to the north, and bordered on the south by the Arkansas Valley. The Oklahoma portion of the range is locally referred to as the Cookson Hills. There are several theories of how the mountains were named, though apparently none are related to the Massachusetts city.
Mount Magazine, officially named Magazine Mountain, is the highest point of the U.S. Interior Highlands and the U.S. state of Arkansas, and is the site of Mount Magazine State Park. It is a flat-topped mountain or mesa capped by hard rock and rimmed by precipitous cliffs. There are two summits atop the mountain: Signal Hill, which reaches 2,753 feet (839 m), and Mossback Ridge, which reaches 2,700 ft (823 m).
The Ouachita Mountains, simply referred to as the Ouachitas, are a mountain range in western Arkansas and southeastern Oklahoma. They are formed by a thick succession of highly deformed Paleozoic strata constituting the Ouachita Fold and Thrust Belt, one of the important orogenic belts of North America. The Ouachitas continue in the subsurface to the northeast, where they make a poorly understood connection with the Appalachians and to the southwest, where they join with the Marathon uplift area of West Texas. Together with the Ozark Plateaus, the Ouachitas form the U.S. Interior Highlands. The highest natural point is Mount Magazine at 2,753 feet (839 m).
The Ordovician Juniata Formation is a mapped bedrock unit in Pennsylvania, West Virginia, Virginia, Tennessee, and Maryland. It is a relative slope-former occurring between the two prominent ridge-forming sandstone units: the Tuscarora Formation and the Bald Eagle Formation in the Appalachian Mountains.
The Fayetteville Shale is a geologic formation of Mississippian age composed of tight shale within the Arkoma Basin of Arkansas and Oklahoma. It is named for the city of Fayetteville, Arkansas, and requires hydraulic fracturing to release the natural gas contained within.
The Flatside Wilderness is a 9,507-acre protected area in the U.S. state of Arkansas. It is one of six wilderness areas in the Ouachita National Forest and also the easternmost. Outdoor enthusiasts can enjoy the area in a number of ways, including an 8.9-mile section of the Ouachita National Recreation Trail.
The Gettysburg Formation is a mapped bedrock unit consisting primarily of sandstones, conglomerates, and shales.
The Hale Formation is a geologic formation in northern Arkansas that dates to the Morrowan Series of the early Pennsylvanian. The Hale Formation has two named members: the Cane Hill and the Prairie Grove Members. The lower member is the Cane Hill, a primarily sandstone and shale interval that unconformably overlies the Mississippian-age Pitkin Formation. The upper member, the Prairie Grove Member, is predominately limestone and conformably underlies the Bloyd Formation.
The Bloyd Formation, or Bloyd Shale, is a geologic formation in Arkansas. It preserves fossils dating back to the Carboniferous period.
Named after Atoka County, Oklahoma, the Atoka Formation is a geologic formation in central and western Arkansas, eastern Oklahoma, central and western Texas, and eastern New Mexico. It is the surface rock of the Boston Mountains and dominates exposures in the Frontal Ouachita Mountains of the Arkansas River Valley.
Tesnus is a ghost town and unincorporated community in Brewster County, in the U.S. state of Texas.
The Mazarn Shale is an Early Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. This interval was first described in 1892, but remained unnamed until 1918 as part of a study by U.S. Geological Survey geologist Hugh Dinsmore Miser.
The Blakely Sandstone is a Middle Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue had initially named this unit the Caddo Shale at a 1907 Geological Society of America meeting, but later redefined and renamed the unit as the Ouachita Shale. He again renamed the unit to the Blakely Sandstone in a letter to Edward Oscar Ulrich, to which Ulrich used in a 1911 publication, becoming the first reference using this name. Ulrich assigned the Blakely Mountain in Garland County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.
The Womble Shale is a Middle Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas, where he named this unit as part of the upper Ouachita Shale and the Stringtown Shale. In 1918, U.S. Geological Survey geologist, Hugh Dinsmore Miser, replaced Purdue's nomenclature with the Womble Shale. Miser assigned the town of Womble in Montgomery County, Arkansas as the type locality. As of 2017, a reference section for this unit has yet to be designated.
The Bigfork Chert is a Middle to Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned the town of Big Fork in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated. The Bigfork Chert is known to produce planerite, turquoise, variscite, and wavellite minerals.
The Polk Creek Shale is a Late Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. First described in 1892, this unit was not named until 1909 by Albert Homer Purdue in his study of the Ouachita Mountains of Arkansas. Purdue assigned Polk Creek in Montgomery County, Arkansas as the type locality, but did not designate a stratotype. As of 2017, a reference section for this unit has yet to be designated.
The Stanley Shale, or Stanley Group, is a Mississippian stratigraphic unit in the Ouachita Mountains of Arkansas and Oklahoma. First described in Arkansas in 1892, this unit was not named until 1902 by J.A. Taff in his study of the Ouachita Mountains of Oklahoma. Taff assigned the town of Stanley in Pushmataha County, Oklahoma as the type locality, but did not designate a stratotype. After introduction into Arkansas in 1909 by Albert Homer Purdue, the unit was redefined in 1918, when the formation known as the Fork Mountain Slate was abandoned and partially combined into the Stanley Shale. As of 2017, a reference section for the Stanley Shale has yet to be designated.
The McAlester Formation is a Pennsylvanian geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. Early descriptions of this unit considered it to be part of the Coal Measures, part of the Upper or Western Coal Bearing Division, the Spadra Stage and part of the Sebastian Stage, and part of the Cavaniol Group. In 1899, J.A. Taff introduced the McAlester Formation name in his study of the Ouachita Mountains of Oklahoma. The name was introduced into Arkansas in 1907 as the McAlester Group, where it consisted of the formations known as the Spadra Shale, the Fort Smith Formation, and the Paris Shale. These formations was redefined and replaced in 1960, when the McAlester Shale replaced the Spadra Shale and the lower Fort Smith Formation. The McAlester Formation is informally recognized with three sub-units in Arkansas: the Lower and Upper Hartshorne coal beds, and the McAlester coal bed. Taff assigned the type locality near the town of McAlester in Pittsburg County, Oklahoma, however he did not state whether the town is the origin of the name. Taff did not designate a stratotype and, as of 2017, a reference section for the McAlester Formation has not been designated.
The Savanna Sandstone or Savanna Formation is a Pennsylvanian geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. Early descriptions of this unit have considered it to be part of the Coal Measures, part of the Upper or Western Coal Bearing Division, part of the Sebastian Stage, and part of the Cavaniol Group. In 1899, J.A. Taff introduced the Savanna Formation name in his study of the Ouachita Mountains of Oklahoma. The name was introduced into Arkansas in 1907, although in 1950, the interval was renamed the Boggy Formation, while the name "Savanna Formation" replaced the underlying interval consisting of the upper Fort Smith Formation and the lower Paris Shale. The Savanna Formation is informally recognized with two named sub-units in Arkansas: the Charleston and Paris coal beds. Taff assigned the type area to the towns of McAlester and Savanna in Pittsburg County, Oklahoma, however he did not state whether the town of Savanna is the origin of the name. Taff did not designate a stratotype, however, a reference section was designated in 1995 in Pittsburg County, Oklahoma.
The Arkoma Basin is a peripheral foreland basin that extends from central west Arkansas to south eastern Oklahoma. The basin lies in between the Ozark Uplift and Oklahoma Platform to the north and Ouachita Mountains to the south and with an area of approximately 33,800 mi2. Along the southern edge of the basin, the Choctaw Fault is the boundary that separates the mountains from the basin itself. This basin is one of seven that lie along the front of the Ouachita and Appalachian mountain systems. This basin is Oklahoma's fourth largest in terms of natural gas production. Oil has been extracted locally, but not on a commercial scale. Coal was the first natural resource used commercially within the basin. Surface mapping of coal seams in the early part of the 20th century lead to the discovery of sub-surface features that indicated the presence of natural gas. Mansfield, Arkansas was the site of the first natural gas discovery in 1902.
