Boston Mountains
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. The Boston Mountains ecoregion has been subdivided into two Level IV ecoregions. Description. The ecoregion is mountainous, forested, and underlain by Pennsylvanian sandstone, shale, and siltstone. It is  one of the Ozark Plateaus; some folding and faulting has occurred but, in general, strata are much less deformed than in the Ouachita Mountains. Maximum elevations are higher, soils have a warmer temperature regime, and carbonate rocks are much less extensive than in the Ozark Highlands. Physiography is distinct from the Arkansas Valley. Upland soils are mostly Ultisols that developed under oak-hickory and oak-hickory-pine forests. Today, forests are still widespread; northern red oak, southern red oak, white oak, and hickories usually dominate the uplands, but shortleaf pine grows on drier, south- and west-facing slopes underlain by  sandstone. Pastureland or hayland occur on nearly level ridgetops, benches, and valley floors. Population density is low; recreation, logging, and livestock farming are the primary land uses. Water quality in streams is generally exceptional; biochemical, nutrient, and mineral water quality parameter concentrations all tend to be very low. Fish communities are mostly composed of sensitive species; a diverse, often darter-dominated community occurs along with nearly equal proportions of minnows and sunfishes. During low flows, streams usually run clear but, during high flow conditions, turbidity in the Boston Mountains tends to be greater than in the Ouachitas. Summer flow in  many small streams is limited or non-existent but isolated, enduring pools may occur. Geology and physiography. The Boston Mountains are a physiographic section of the larger Ozark Plateaus province, which in turn is part of the larger Interior Highlands physiographic division. The area is underlain by Pennsylvanian sandstone, shale, and siltstone, where some folding and faulting has occurred. The sandstone beds become thinner, but more shaly in the west as the mountains decline in elevation. The range covers an area of . The rocks of the region are essentially little disturbed, flat-lying sedimentary layers of the Paleozoic age. The  highest ridges and peaks are capped by Pennsylvanian sandstone and shale. The deeply eroded valleys are cut into Mississippian limestones and below that layer Ordovician dolomites. General description. The Boston Mountains form the southwestern part of the Ozark plateau where they are the highest portion of the Ozarks. Summits can reach elevations of just over with valleys to deep. Turner Ward Knob (TWK) is the highest named peak. Located in western Newton County, Arkansas, its elevation is . Nearby, five unnamed peaks have elevations at or slightly above . Two of these highest peaks are located west of Turner Ward Knob, one  being the location of the Buffalo Lookout fire tower at . The other three highest peaks are located south-southwest of Turner Ward Knob along Arkansas Highway 16. Rivers and streams. The Boston Mountains are the source of rivers and streams that flow out from the mountains in all directions. Within a radius of a point just west of the summits discussed above are located the sources of the White River, the Buffalo River, the Kings River, War Eagle Creek, and Little Mulberry Creek. Other rivers and streams having their headwaters in the Boston Mountains include the Illinois River, the Mulberry  River, Lee Creek, Frog Bayou, Big Piney Creek, Illinois Bayou, and the Little Red River. To the south, the Arkansas River valley separates the Boston Mountains from the Ouachita Mountains. In Arkansas, the Boston Mountains are found in the following counties: Boone, Carroll, Cleburne, Conway, Crawford, Franklin, Independence, Johnson, Madison, Newton, Pope, Searcy, Stone, Van Buren, and Washington. In Oklahoma, the Boston Mountains are found in these counties: Adair, Cherokee, Muskogee, Sequoyah, and Wagoner.