The term Cross Timbers, also known as
Ecoregion
An ecoregion (ecological region) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...
29, Central Oklahoma/Texas Plains, is used to describe a strip of land in the
United States
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...
that runs from southeastern
Kansas
Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
across
Central Oklahoma
Central Oklahoma is the geographical name for the central region of the U.S. state of Oklahoma. It is also known by the Oklahoma Department of Tourism and Recreation, Oklahoma Department of Tourism designation, Frontier Country, defined as the 12 ...
to
Central Texas.
Made up of a mix of
prairie
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
,
savanna
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...
, and
woodland,
it forms part of the boundary between the more heavily forested eastern country and the almost treeless
Great Plains
The Great Plains is a broad expanse of plain, flatland in North America. The region stretches east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. They are the western part of the Interior Plains, which include th ...
,
and also marks the western
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
limit of many
mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s and
insect
Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
s.
No major metropolitan areas lie wholly within the Cross Timbers, although roughly the western half of the
Dallas-Fort Worth Metroplex does, including the cities of
Fort Worth
Fort Worth is a city in the U.S. state of Texas and the county seat of Tarrant County, Texas, Tarrant County, covering nearly into Denton County, Texas, Denton, Johnson County, Texas, Johnson, Parker County, Texas, Parker, and Wise County, Te ...
,
Denton,
Arlington, and
Weatherford.
The western
suburb
A suburb (more broadly suburban area) is an area within a metropolitan area. They are oftentimes where most of a metropolitan areas jobs are located with some being predominantly residential. They can either be denser or less densely populated ...
s of the
Tulsa metropolitan area and the northeastern suburbs of the
Oklahoma City metropolitan area
The Oklahoma City metropolitan area is an urban region in Central Oklahoma. It is the largest metropolitan area in the state of Oklahoma and contains the state capital and principal city, Oklahoma City. It is often known as the Oklahoma City Metr ...
also lie within this area.
The main highways that cross the region are
I-35 and
I-35W going north to south (although they tend to skirt the Cross Timbers' eastern fringe south of Fort Worth) and
I-40 going east to west. Numerous
U.S. Highways also cross the area.
I-35 means a portion of Austin and Travis County is also included in the Cross Timbers.
As an ecoregion
The Cross Timbers are defined by the
United States Environmental Protection Agency
The Environmental Protection Agency (EPA) is an independent agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on De ...
as Ecoregion 29, a
Level III ecoregion. Some organizations and maps refer to the Cross Timbers ecoregion as the Central Oklahoma/Texas Plains.
The Cross Timbers are contained within the
WWF central forest-grasslands transition ecoregion.
The woodland and savanna portions of the Cross Timbers are mainly
post oak and
blackjack oak on coarse, sandy soils;
fire suppression in recent years has increased forest density and allowed
eastern redcedar to invade as well. The short, stout oaks that grow in the Cross Timbers were not usable as timber, and those that were not cleared for farmland constitute one of the least disturbed forest types in the eastern United States, with some of
old-growth forest scattered throughout the region.
These old-growth forests contain millions of post oak from 200 to 400 years old and red cedar over 500 years old.
The prairie portions are chiefly
tallgrass on finer, dry soils.
Overall, the Cross Timbers are not as
arable as the surrounding ecoregions.
Today,
land use
Land use is an umbrella term to describe what happens on a parcel of land. It concerns the benefits derived from using the land, and also the land management actions that humans carry out there. The following categories are used for land use: fo ...
is a mixture of
rangeland,
pastures, and
farmland.
The area has also been an important site of
oil extraction for over 80 years.
Geologically speaking, the Cross Timbers are underlain by
Pennsylvanian and
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
-era
sandstone
Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
and
limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
that has been moderately
dissected, giving the region a gently to moderately rolling
topography
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps.
Topography is a field of geoscience and planetary sci ...
,
including some
cuestas.
Although local
relief
Relief is a sculpture, sculptural method in which the sculpted pieces remain attached to a solid background of the same material. The term ''wikt:relief, relief'' is from the Latin verb , to raise (). To create a sculpture in relief is to give ...
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.
Ecologically, the EPA includes the Cross Timbers as part of the vast
Great Plains
The Great Plains is a broad expanse of plain, flatland in North America. The region stretches east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. They are the western part of the Interior Plains, which include th ...
, which comprise Level I Ecoregion 9.0, stretching from
central Alberta in
Canada
Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
to northern
Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
. More specifically, the Cross Timbers fall into Level II Ecoregion 9.4, the smaller South Central Semi-Arid Plains. 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.
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
Chautauqua ( ) is an adult education and social movement in the United States that peaked in popularity in the late 19th and early 20th centuries. Chautauqua assemblies expanded and spread throughout rural America until the mid-1920s. The Cha ...
and
Elk counties and smaller portions of
Greenwood,
Woodson,
Wilson, and
Montgomery counties, while in Oklahoma, this region covers all of
Seminole
The Seminole are a Native American people who developed in Florida in the 18th century. Today, they live in Oklahoma and Florida, and comprise three federally recognized tribes: the Seminole Nation of Oklahoma, the Seminole Tribe of Florida, ...
,
Pottawatomie, and
Okfuskee counties, large parts of
Osage,
Lincoln,
Creek,
Oklahoma
Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...
,
Cleveland
Cleveland is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located along the southern shore of Lake Erie, it is situated across the Canada–U.S. maritime border and approximately west of the Ohio-Pennsylvania st ...
,
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.
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
Waco ( ) is a city in and the county seat of McLennan County, Texas, United States. It is situated along the Brazos River and Interstate 35, I-35, halfway between Dallas and Austin, Texas, Austin. The city had a U.S. census estimated 2024 popul ...
. 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.
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
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...
,
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.
The part of this region north of
I-20 is sometimes colloquially referred to as the
Palo Pinto Mountains;
the hills are isolated, rugged, and scenic, with spectacular
bluffs along the
Brazos River as it flows through the region.
Coal mining
Coal mining is the process of resource extraction, extracting coal from the ground or from a mine. Coal is valued for its Energy value of coal, energy content and since the 1880s has been widely used to Electricity generation, generate electr ...
has historically been an important activity, as
bituminous coal
Bituminous coal, or black coal, is a type of coal containing a tar-like substance called bitumen or asphalt. Its coloration can be black or sometimes dark brown; often there are well-defined bands of bright and dull material within the coal seam, ...
deposits are found throughout the region; indeed, the town of
Newcastle in Young County was named after the
English city of the same name due to the coal connection.
In the mid-to-late 19th century,
Comanche Indians occupied this area, and it became a flash point for conflict between various groups of white settlers, the Comanche, and the
U.S. Cavalry;
Forts
A fortification (also called a fort, fortress, fastness, or stronghold) is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from ...
Belknap and
Richardson were built in the area to protect this part of the frontier.
Numerous roads cross this region, including
US 70 in Oklahoma and
I-20,
I-30,
US 67,
US 81,
US 82,
US 180,
US 183,
US 281,
US 287, and
US 380 in Texas.
29d: Grand Prairie
A fairly narrow strip dividing the Eastern and Western Cross Timbers, the Grand Prairie differs in
physiography
Physical geography (also known as physiography) is one of the three main branches of geography. Physical geography is the branch of natural science which deals with the processes and patterns in the natural environment such as the atmosphere, h ...
,
topography
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps.
Topography is a field of geoscience and planetary sci ...
, and land use from both of these, as it is much more nearly level and better suited to
agriculture
Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...
.
It includes a small part of
Love County, Oklahoma (the only part of this region outside of Texas) and passes south through western
Cooke County, eastern
Wise County, and western
Denton,
Tarrant, and
Johnson counties, and also includes parts of
Parker,
Erath,
Hood,
Somervell,
Hill
A hill is a landform that extends above the surrounding terrain. It often has a distinct summit, and is usually applied to peaks which are above elevation compared to the relative landmass, though not as prominent as Mountain, mountains. Hills ...
, and
McLennan counties. This region contains the cities of
Fort Worth
Fort Worth is a city in the U.S. state of Texas and the county seat of Tarrant County, Texas, Tarrant County, covering nearly into Denton County, Texas, Denton, Johnson County, Texas, Johnson, Parker County, Texas, Parker, and Wise County, Te ...
,
Granbury and
Denton, although Denton lies on the border with the Eastern Cross Timbers.
I-35 and I-35W cross north to south, while
US 82,
US 380,
I-30,
I-20,
US 377, and
US 67 cross east to west;
US 81 and
US 287 also cross southwest to northeast.
29e: Limestone Cut Plains
A broader, southern extension of the Grand Prairie, found only in Texas; it is underlain by limestone rather than sandstone, and serves as a physiological and vegetational transition to the Edwards Plateau, which it borders to the south. All of
Hamilton
Hamilton may refer to:
* Alexander Hamilton (1755/1757–1804), first U.S. Secretary of the Treasury and one of the Founding Fathers of the United States
* ''Hamilton'' (musical), a 2015 Broadway musical by Lin-Manuel Miranda
** ''Hamilton'' (al ...
and
Coryell counties, large parts of
Bell
A bell /ˈbɛl/ () is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be m ...
,
Lampasas,
Mills,
Erath, and
Bosque counties, and smaller parts of
Williamson,
Burnet,
Brown,
Comanche,
Hood,
Somervell, and
McLennan counties, including the towns of
Killeen,
Copperas Cove, and
Lampasas as well as the
Fort Cavazos Army
An army, ground force or land force is an armed force that fights primarily on land. In the broadest sense, it is the land-based military branch, service branch or armed service of a nation or country. It may also include aviation assets by ...
base, fall within this region.
Among the few major roads that cross the Limestone Cut Plains are
US 281 north to south and
US 84 east to west.
29f: Carbonate Cross Timbers
This ecoregion exists as an
enclave
An enclave is a territory that is entirely surrounded by the territory of only one other state or entity. An enclave can be an independent territory or part of a larger one. Enclaves may also exist within territorial waters. ''Enclave'' is so ...
within the Western Cross Timbers, stretching from southern
Jack County, Texas across northwestern
Palo Pinto County into eastern
Stephens County, as well as tiny parts of
Young and
Eastland counties. The region features a limestone substrate as opposed to sandstone, and has greater topographical relief and denser and different vegetation than other parts of the Cross Timbers. No towns of any size lie within this area, although
Possum Kingdom Lake and
State Park
State parks are parks or other protected areas managed at the sub-national level within those nations which use "Federated state, state" as a political subdivision. State parks are typically established by a state to preserve a location on accou ...
do;
the region is crossed by
US 180 and
Texas State Highway 16.
29g: Arbuckle Uplift
Covering a fairly small area in south-central Oklahoma and underlain by a unique mosaic of several different
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
s, this region includes the town of
Ardmore.
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
sugar maple,
bur oak, and
live oak in deeper river canyons. The towns of
Duncan, Oklahoma and
Walters, Oklahoma
Walters is a town in Cotton County, Oklahoma, United States. Its population was 2,412 as of the 2020 United States census. The city, nestled between twin creeks, is the county seat of Cotton County. The city's motto is "Small Town; Big Heart" ...
, lie in this region.
29i: Arbuckle Mountains
The
Arbuckle Mountains are located in a small area nestled in between regions 29g and h; it is made of
folded, rather than dissected, limestone, sandstone, and
dolomite, and features the greatest topographical relief of the entire Cross Timbers, though not the highest elevations. The landscape includes many caves,
sinkholes,
springs, and streams.
I-35 crosses this region north to south.
Climatology
Part of the difference in the Cross Timbers region and the surrounding regions west (drier) and east (wetter) has to do with the
dry line
A dry line (also called a dew point line, or Marfa front, after Marfa, Texas) is a line across a continent that separates moist air and dry air. One of the most prominent examples of such a separation occurs in central North America, especially ...
which separates humid air from the
Gulf of Mexico
The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
from the dry air of the
Llano Estacado, the
Texas Panhandle, and the
High Plains.
History
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."
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."
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.
Robert Neighbors and
Rip Ford reached the "Cross Timbers, two parallel strips of timber region that ran down the middle of Texas", in 1849 while blazing an emigrant trail from Austin to El Paso.
[Ford, J.S., 1963, Rip Ford's Texas. Austin: University of Texas Press, ]
See also
*
Dry line
A dry line (also called a dew point line, or Marfa front, after Marfa, Texas) is a line across a continent that separates moist air and dry air. One of the most prominent examples of such a separation occurs in central North America, especially ...
*
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.
* Francaviglia, Richard V. ''The Cast Iron Forest: A Natural and Cultural History of the North American Cross Timbers''. University of Texas Press, 2000.
*
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.
* McLeran, Vic. ''The Cooper's Hawk: A Cross Timbers Chronicle''. Philadelphia: Xlibris Corporation, 2000. and
Further reading
* Dale, Edward Everett. ''The Cross Timbers: Memories of a North Texas Boyhood''. Austin, TX: University of Texas Press, 1966.
* Roach, Joyce. ''Wild Rose: A Folk History of a Cross Timbers Settlement, Keller, Texas''. Denton, TX: University of North Texas Press, 1996.
References
External links
The Ancient Cross Timbers ConsortiumMap of Cross TimbersTexas counties map showing the ecoregion
Texas counties map showing the ecoregion; similar to the above map
This collection by wildflower.org lists native plants local to the Texas part of 29.* https://www.epa.gov/eco-research/ecoregion-download-files-state-region-6#pane-41 Under "Texas." 4 maps contain additional information on Cross Timbers, such as which plants grow in the level IV ecoregions. The maps have county borders but no names; however, they detail rivers, lakes, and major cities, and contain photographs. There is also a Texas ecoregion report PDF which describes Cross Timbers vegetation and other features in much more detail than the maps. Under "Oklahoma," there is no ecoregion report PDF yet but more details are contained in the 4 PDF maps.
* https://www.epa.gov/eco-research/ecoregion-download-files-state-region-7#pane-14 Under "Kansas," there is no ecoregion report PDF yet but more details are contained in the 4 map PDFs.
* https://www.plantmaps.com/ Entering a Zip code reveals which of the level IV ecoregions it falls under.
Cross Timbers Historic Images Project–Texas*
Oklahoma Digital Maps: Digital Collections of Oklahoma and Indian Territory
{{coord, 34, 00, N, 97, 15, W, display=title
Grasslands of the United States
Temperate grasslands, savannas, and shrublands in the United States
Ecoregions of the United States
Plains of the United States
South Central United States
Geographic regions of Oklahoma
Regions of Kansas
Regions of Texas
Grasslands of Kansas
Grasslands of Oklahoma
Grasslands of Texas