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Triassic Basins

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About the Triassic Basins

The Triassic Basins, referred to in some documents as the Triassic Uplands, is a region of the Piedmont consisting of six separate pieces, including three relatively larger basins and three smaller ones, extending through Virginia and North Carolina, and barely into South Carolina.

This region consists of irregular plains with low, rounded hills, ridges, and valleys. The area is underlain mostly by sedimentary rock, with a few intrusions of diabase, contrasting with the metamorphic rock of the surrounding regions. The region formed when these rocks, which are newer than their surroundings, were pushed down by faulting into a deeper layer of older rock.

Original vegetation here has been mapped as Oak-Hickory-Pine forest, dominated by various hickories, shortleaf pine (Pinus echinata), loblolly pine (Pinus taeda), white oak (Quercus alba), and post oak (Quercus stellata).

There is significant agriculture in the area, including production of corn, tobacco, cotton, soybeans, small grains, and truck crops. Many forests are found on abandoned fields, and consist of an early-successional stage of shortleaf pine, loblolly pine, virginia pine (Pinus virginiana), and a variety of hardwoods. Where enclosed by the Northern Inner Piedmont, the landscape here is not appreciably different from the surroundings, but where enclosed instead by the Northern Outer Piedmont, the landscape in this region is relatively more forested. The basin west of Richmond, VA has significant suburban development, and farther southwest, the largest basin contains the city of Durham, NC. This basin has also seen significant damming and creation of artificial reservoirs.

The various parts of this region are surrounded by different regions; the long, narrow stretch fathest inland is surrounded by the Northern Inner Piedmont. The two eastern portions in Virginia are surrounded by the Northern Outer Piedmont, which borders but does not surround the largest basin, in North Carolina. In North Carolina the two largest regions border the Carolina Slate Belt, and in a small area, the Sand Hills. The largest region also shares a small border directlly with the Rolling Coastal Plain. A tiny, isolated portion of this region also borders the Southern Outer Piedmont.

References

1. Woods, A.J, Omernik, J.M., Brown, D.D. "Level III and IV Ecoregions of Delaware, Maryland, Pennsylvania, Virginia, and West Virginia", U.S. Environmental Protection Agency: National Health and Environmental Effects Research Laboratory, Corvallis, OR (1999) Web.