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Northern Piedmont

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NameColor on MapEPA Code‡
Triassic Lowlands64a
Trap Rock and Conglomerate Uplands64b
Piedmont Uplands64c
Piedmont Limestone/Dolomite Lowlands64d
Glaciated Triassic Lowlands64e
Passaic Basin Freshwater Wetlands64f
Hackensack Meadowlands64g

† Status: ✓ = Complete ○ = Needs Image … = Incomplete ∅ = Stub Only

This code refers to the US EPA's Level 4 ecoregion codes for the continental U.S., see here.


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About the Northern Piedmont

The Northern Piedmont is a region stretching northeast-southwest, located between the Appalachian mountains to the northwest and the coastal plain to the southeast. The region is widest in Maryland and Pennsylvania, and extends into New York, New Jersey and Virginia.

The climate here is transitional between a humid subtropical climate and a colder-winter humid continental climate in the north. However winter lows often vary more year-to-year than they do across the length of this region. There are four well-defined seasons, and precipitation is similar year-round.

The terrain here is intermediate between the mountains to the northwest and the flatter coastal plain to the southeast. There are rolling hills, irregular plains, and open valleys. Geologically, this region is diverse, with a mix of metamorphic, igneous, and sedimentary rocks, leading to different soil types and variations in topography in different subregions. Soils range from some of the mort fertile soils for agriculture in the limestone bottomlands, to thin, poorly-developed, rocky soils on ridges and rock outcroppings. These thin soils vary widely in pH, with radically different environments existing on outcroppings of limestone, diabase, quartzite, and in places, serpentine minerals. The northeasternmost portion of this region was glaciated and also features soils formed on glacial till and moraines.

Before European settlement, this region was mostly covered in Appalachian oak forest, on the well-drained uplands that covered most of the area. Dominant trees here included American chestnut (Castanea dentata), chestnut oak (Quercus montana), white oak (Quercus alba), northern red oak (Quercus rubra), various hickories, white ash (Fraxinus americana), elm, and tuliptree (Liriodendron tulipifera).

Most of the forests here have been cleared, and the composition of the remaining forests has been greatly changed. American Chestnut has been virtually eliminated by the Chestnut blight, and American elm greatly reduced in numbers. Eastern redcedar (Juniperus virginiana) is abundant on abandoned farmland and other cleared areas. Numerous invasive trees have become established, including tree of heaven (Ailanthus altissima), which is mainly found in urban areas and along roadways, and Norway maple (Acer platanoides), which also invades forests. There is significant agriculture as well as industry, urbanization, and suburban development. This area includes a portion of the metro areas of Washington D.C., Baltimore, Philadelphia, and New York City as well as numerous smaller cities. Agriculture here is intense and diversified on areas with limestone and dolomite soils, occasional on flatter areas with other soils, whereas the more rugged uplands, with steeper slops and thinner, rockier soils, are mostly left as forest.

To the northwest, this region is bordered by various mountainous regions, parts of the Appalachians: in the south, by the Blue Ridge, farther north by the Ridge and Valley region, and at the very north, by the Northeastern Highlands. To the southeast, there is a fall line marking the beginning of the coastal plain, and this region borders the Southeastern Plains, and farther north, the Middle Atlantic Coastal Plain, and in a small area to the northeast, the Atlantic Coastal Pine Barrens. The southern border of this region is a gradual transition to the similar but warmer Piedmont. At the north, this region borders the Northeastern Coastal Zone.

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1. Wiken, E., Griffith, G. "North American Terrestrial Ecoregions - Level III", Commission for Environmental Cooperation, (2011) Web.