Cross Timbers

The term Cross Timbers, also known as Ecoregion 29, Central Oklahoma/Texas Plains, is used to describe a strip of land in the United States that runs from southeastern Kansas across Central Oklahoma to Central Texas.^[1] Made up of a mix of prairie, savanna, and woodland,^[2][3] it forms part of the boundary between the more heavily forested eastern country and the almost treeless Great Plains,^[2][3][4] and also marks the western habitat limit of many mammals and insects.^[2]

No major metropolitan areas lie wholly within the Cross Timbers, although roughly the western half of the

Geologically speaking, the Cross Timbers are underlain by Pennsylvanian and Cretaceous-era sandstone and limestone that has been moderately dissected, giving the region a gently to moderately rolling topography,^[3][4] including some cuestas.^[2] Although local relief is relatively low, it is generally greater than that in the surrounding ecoregions, although this is not the case with the Flint Hills in Kansas.^[4]

Ecologically, the EPA includes the Cross Timbers as part of the vast Great Plains, which comprise Level I Ecoregion 9.0, stretching from central Alberta in Canada to northern Mexico.^[6] More specifically, the Cross Timbers fall into Level II Ecoregion 9.4, the smaller South Central Semi-Arid Plains.^[7] In southern Oklahoma, the Cross Timbers are located on the very edge of the Great Plains, as they border directly parts of Level I Ecoregion 8.0, the Eastern Temperate Forests; elsewhere, the Cross Timbers are separated slightly from the Eastern Temperate Forests.^[2] In turn, the Cross Timbers are themselves subdivided into nine Level IV Ecoregions:

29a: Northern Cross Timbers

This is a wide belt of land stretching from south-central Oklahoma into southeastern Kansas and is the only part of the Cross Timbers that extends into Kansas. In that state, it covers eastern Chautauqua and Elk counties and smaller portions of Greenwood, Woodson, Wilson, and Montgomery counties, while in Oklahoma, this region covers all of Seminole, Pottawatomie, and Okfuskee counties, large parts of Osage, Lincoln, Creek, Oklahoma, Cleveland, Pontotoc, Hughes, McIntosh, and Okmulgee counties, and smaller parts of Logan, Garvin, Murray, Pawnee, Tulsa, Wagoner, and Washington counties. The towns of Sand Springs, Sapulpa, Ada, and Shawnee, Oklahoma fall within this large area; Bartlesville and Okmulgee lie on the eastern edge.^[2][4]

29b: Eastern Cross Timbers

In Oklahoma, this belt of woodland covers all of Marshall County and parts of Love, Carter, Johnston, and Bryan counties, but in Texas, this region exists as a long, very narrow strip of dense forest stretching from the Red River to just north of Waco, Texas. It passes through northwestern Grayson County, eastern Cooke, Denton and Tarrant counties, central Johnson County, western Hill County, and northern McLennan County. The city of Arlington, Texas lies within this zone, and Denton and Cleburne are on its eastern edge.^[2][8]

29c: Western Cross Timbers

A much wider band than the Eastern Cross Timbers, the Western Cross Timbers band extends from far southern Oklahoma, including parts of Love and Carter counties, into central Texas, where it covers large parts of Montague, Young, Jack, Wise, Stephens, Palo Pinto, Parker, Eastland, Erath, Brown, San Saba, and Mills counties, as well as smaller parts of Clay, Cooke, Callahan, Hood, Coleman, and McCulloch counties. In Texas, this area includes the towns of Weatherford and Mineral Wells; Stephenville lies on the eastern fringe, while Brownwood is on the western edge.^[2][8]

The part of this region north of I-20 is sometimes colloquially referred to as the Palo Pinto Mountains;^[9][10][11] the hills are isolated, rugged, and scenic, with spectacular bluffs along the Brazos River as it flows through the region.^[9][10][12]

Coal mining has historically been an important activity, as bituminous coal deposits are found throughout the region;^[13] indeed, the town of Newcastle in Young County was named after the English city of the same name due to the coal connection.^[14]

In the mid-to-late 19th century,

Covering a fairly small area in south-central Oklahoma and underlain by a unique mosaic of several different minerals, this region includes the town of Ardmore.^[2]

29h: Northwestern Cross Timbers

An extension in two branches of the Cross Timbers into southwestern Oklahoma, this area features reduced tree density and height, but also small forests dominated by

The thick growth formed an almost impenetrable barrier for early American explorers and travelers. Washington Irving, in 1835, described it as "like struggling through forests of cast iron."^[16] Rachel Plummer, while a captive of the Comanche in 1836, described it as "a range of timber-land from the waters of Arkansas, bearing a southwest direction, crossing the False Ouachita, Red River, the heads of Sabine, Angelina, Natchitoches, Trinity, Brazos, Colorado...the range of timber is of an irregular width, say 5 to 35 miles wide...abounding with small prairies, skirted with timber of various kinds — oak, of every description, ash, elm, hickory, walnut and mulberry...the purest atmosphere I ever breathed was that of these regions."^[17] Josiah Gregg described the Cross Timbers in 1845 as varying in width from five to thirty miles and attributed their denseness to the continual burning of the prairies.^[18]

The Cross Timbers vary in width from five to thirty miles, and entirely cut off the communication betwixt the interior prairies and those of the great plains. They may be considered as the "fringe" of the great prairies, being a continuous brushy strip, composed of various kinds of

shin-oak." Most of the timber appears to be kept small by the continual inroads of the "burning prairies;" for, being killed almost annually, it is constantly replaced by scions of undergrowth; so that it becomes more and more dense every reproduction. In some places, however, the oaks are of considerable size, and able to withstand the conflagrations. The Underwood is so matted in many places with grapevines, green-briars, etc., as to form almost impenetrable "roughs," which serve as hiding-places for wild beasts, as well as wild Indians; and would, in savage warfare, prove almost as formidable as the hammocks of Florida

.

— Josiah Gregg

• Dry line
• History of Texas forests

Bibliography

• Anderson, Roger C., James S Fralish, Jerry M. Baskin (eds.). Savannas, Barrens, and Rock Outcrop Plant Communities of North America. Cambridge University Press, 1999.
  ISBN 0-521-57322-X
• Francaviglia, Richard V. The Cast Iron Forest: A Natural and Cultural History of the North American Cross Timbers. University of Texas Press, 2000.
  ISBN 0-292-72515-9
• Gregg, Josiah. "The Cross Timbers". Commerce of the Prairies. 1845. V. II, Ch. 10, pp. 199–201. (accessed June 19, 2007: hosted by The Kansas Collection)
• Irving, Washington. A Tour on the Prairies, Chapter XXI. 1835.
• Johnson, Neil R. (ed. C. Neil Kingsley). The Chickasaw Rancher. University Press of Colorado, 2001.
  ISBN 978-0-87081-635-2
• McLeran, Vic. The Cooper's Hawk: A Cross Timbers Chronicle. Philadelphia: Xlibris Corporation, 2000.
  ISBN 0-7388-5934-6^{[self-published source?}
  ]

• Dale, Edward Everett. The Cross Timbers: Memories of a North Texas Boyhood. Austin, TX: University of Texas Press, 1966.
  ISBN 0-292-73611-8
• Roach, Joyce. Wild Rose: A Folk History of a Cross Timbers Settlement, Keller, Texas. Denton, TX: University of North Texas Press, 1996.
  ISBN 0-89865-972-8