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Lower Canadian Hills

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About the Lower Canadian Hills

The Lower Canadian Hills are a region located at the far western end of the Arkansas Valley, located entirely within Oklahoma. This region can be seen as a transition between the drier Cross Timbers region to the west and the moister parts of the Arkansas Valley to the east.

This region consists of hills and valleys, with scattered ridges, numerous small ponds, and occasional larger lakes. This region is underlain by bedrock of shale and sandstone, with some coal, but it is also covered in extensive terrace and river deposits, and residuum left by the weathering of water-soluble rocks, which is a mix of sandy loam and silty clay-loam.

The climate is humid and subtropical, but somewhat drier than areas to the east. Precipitation is seasonal, following a bimodal pattern with dry summers and winters, and precipitation peaking in May and again in October. The change in rainfall as one moves west however is also seasonal: the spring rainy season is as wet or even wetter than areas to the east, but this area has markedly drier autumns than areas to the east.

Natural vegetation cover here is not well known, but was probably a mix of cross timbers, tallgrass prairie, oak-hickory forest, and oak-hickory-pine forest. Lusher deciduous forests could be found along streams. Areas of cross timbers featured blackjack oak, post oak, eastern redcedar, and little bluestem. Tallgrass prairie featured big bluestem, little bluestem, switchgrass, and Indiangrass.

Present use is a mix of pastureland, cropland, and woodland. Major crops here include soybeans, wheat, grain sorghum, alfalfa, peanuts, and corn. There is also strip mining for coal extraction. Acid mine runoff has degraded water quality in some streams. There is also a small amount of natural gas extraction. Forest cover is mostly on the more rugged upland sites, although there are also some forested floodplains. On flatter upland terraces, mixed deciduous forests feature post oak, black oak, southern red oak, and black hickory. Hills and ridges support post oak, blackjack oak, white oak, various hickories, eastern redcedar, and shortleaf pine. Floodplain forests feature eastern cottonwood, American sycamore, bottomland oaks, black willow, green ash, pecan, sweetgum, and black walnut. Although there is significant wild forest in this region, there is little to no public or protected land.

This region is bordered to the north-northwest by the Northern Cross Timbers, to the southwest by the Arbuckle Uplift, in a small border to the south by the Cretaceous Dissected Uplands, and to the south-southeast by the Fourche Mountains. In the east it is mostly bordered by the Arkansas Valley Plains, except for an area where it borders an intrusion of the Scattered High Ridges and Mountains.

References

1. Woods, A.J., Omernik, J.M., Butler, D.R., Ford, J.G., Henley, J.E., Hoagland, B.W., Arndt, D.S., and Moran, B.C. "Ecoregions of Oklahoma (Poster)", Reston, VA, U.S. Geological Survey (2005) Web.