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Enter. West Virginia Physiographic Provinces The Appalachian region containing West Virginia is subdivided into physiographic provinces. To learn more.

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Presentation on theme: "Enter. West Virginia Physiographic Provinces The Appalachian region containing West Virginia is subdivided into physiographic provinces. To learn more."— Presentation transcript:

1 Enter

2 West Virginia Physiographic Provinces The Appalachian region containing West Virginia is subdivided into physiographic provinces. To learn more about a physiographic province click on the name above. Appalachian Plateau Appalachian Plateau Valley and Ridge Valley and Ridge Great Valley Great Valley Blue Ridge Blue Ridge Piedmont and Coastal Plain Piedmont and Coastal Plain From west to east these provinces are: When you see this symbol, click on it and it will return you to this page. Back A physiographic province is a region of which all parts are similar in geologic structure and climate and had a unified geomorphic history; a region whose pattern of landforms differ significantly from that of adjacent regions. A physiographic province is unique due to the relationship of geology to geography. It is important to remember that the surface expression (geology) is controlled by the geology upon which it has formed. {

3 The Appalachian Plateau Province covers nearly 70% of the State’s surface area. Everywhere under the plateau the layers of sedimentary rock are flat or nearly flat. If you have been to Blackwater Falls or to Parkersburg you have been on the plateau. But, you probably noticed that the land was different in these two places - one was more rugged than the other. For this reason the Appalachian Plateau is subdivided into the Low and High segments. Appalachian Low Plateau Appalachian Low Plateau Physiographic Province Physiographic Province Appalachian High Plateau Appalachian High Plateau Physiographic Province Physiographic Province Appalachian Plateau Back

4 Appalachian Low Plateau Physiographic Province The Appalachian Low Plateau is largely underlain by rocks of Pennsylvanian age that appear perfectly horizontal in roadcuts and outcrops. The rocks appear horizontal because the dips of the fold limbs are less than 2 or 3 degrees which the human eye cannot discern. The dominant stream drainage pattern throughout is dendritic with streams having progressed to the mature stage with most having well-developed floodplains and meanders. Also characteristic of mature topography, the relief of the region is measured in a few hundred feet with the hills between major streams possessing rounded summits and relatively shallow slopes.dips of the fold limbsdendritic Back

5 This phrase is “geology talk” for the tilt or inclination of the rocks. West Virginia’s sedimentary rocks were originally formed as flat-laying layers. However, in some places these layers have been deformed (folded) into shapes called anticlines and synclines. Dip refers to the tilt of the limbs (sides) of the fold away from the axis or axial plane. Symmetrical Asymmetrical OverturnedRecumbent Monocline Anticline Syncline Anticlines and Synclines “Dips of the fold limbs” Axial plane shown by dashed lines Back

6 Dendritic Stream Drainage Trellis Stream Drainage Back

7 Appalachian High Plateau Physiographic Province The Appalachian High Plateau extends from the western base of Chestnut Ridge in the west to the Allegheny Structural Front on the east. Rocks within the province range in age from Pennsylvanian to Devonian with the oldest rocks being exposed in the middle of breached anticlines. The dominant geologic structures within the High Plateau are symmetrically folded sedimentary rocks. Correspondingly, the area displays a more rugged topography than that seen in the Low Plateau. This increased relief has resulted in the High Plateau being referred to historically as part of the Allegheny Mountains or “open-fold portion” of the Appalachian Plateau.Allegheny Structural Front A breached anticline is one that has had the top removed by weathering and erosion. These processes expose the older rocks in the middle of the anticline. A classic West Virginia breached anticline is Canaan Valley. Back

8 Allegheny Structural Front

9 The Valley and Ridge Physiographic Province extends from the Allegheny Structural Front to the Great Valley and constitutes most of what is commonly referred to as the Appalachian Mountains. The Valley and Ridge is dominated by NE-SW- trending parallel valleys and ridges made of asymmetric to overturned anticlines. The wavelength of the anticlines is significantly less than the wavelength of the folds in the High Plateau to the west. Many of the anticlinal structures have been breached by erosion, exposing Ordovician age rocks, the oldest rocks of this region. In contrast to the Plateau, stream drainage has been arranged into a trellis pattern.asymmetric to overturned anticlinestrellis Back Valley and Ridge

10 Symmetric anticlines and synclines. Overturned anticlines and synclines. Asymmetric anticlines and synclines. Back

11 Dendritic Stream Drainage Trellis Stream Drainage Back

12 The Great Valley, commonly referred to as the Shenandoah Valley, is between the Valley and Ridge and Blue Ridge Mountains Provinces. Rocks within the Great Valley are nearly all Cambrian and Ordovician limestones. The red to orange color of the soil is typical of soils derived from limestones and is due to the Fe 2 O 3 contained in the original insoluble residue. Surprisingly, this large valley has formed on top of a complicated geologic foundation.Cambrian and Ordovician limestonescomplicated geologic foundation Back Great Valley

13 Valley and Ridge Remember this factoid: Limestone = Carbonate = CaCO 3 CaCO 3 is water-soluble. As a result, the carbonate rocks of the Valley and Ridge Province rocks have been dissolved down to the mean stream level, resulting in a broad, flat valley. The few low ridges seen within the valley are largely the result of the occasional non-carbonate rock layer. Typical of regions underlain by limestones, the soils are thin and are composed entirely of the clay minerals and quartz that comprised the insoluble residue of the original limestones. Also typical of regions underlain by limestones, the Great Valley shows extensive development of karst topography. The soils are ideal for the growth of grass which explains the wide-spread use of the land for grazing of cattle. Many of the carbonate rocks within the Great Valley are so pure that they have been quarried and deep-mined for flux stone for the iron and steel industry, for the production of cement, to coat the walls of deep coal mines in order to reduce the amount of flammable coal dust in the atmosphere, and to inhibit the formation of acid mine drainage from the exposure of sulfur-rich coal-associated rocks. Back “insoluble” means “will not dissolve.” Carbonate (limestone) rocks are not a pure material. Within the structure of the rock there is dirt, minerals, and pieces of other rock types. If the carbonate material is completely dissolved by an acid, what remains is the insoluble residue. Sometimes the residue contains iron. As the iron “rusts,” a red soil may be formed. In some areas, like Greenbrier County, much of the rock is limestone (carbonate). As acidic rain water and ground water flows over and through the limestone, they may dissolve that portion of the rock which they contact. Eventually, caves, caverns, sinkholes, and lost rivers develop in these limestone- rich areas. The soils in these areas are ideal for the growth of grass.

14 Great Valley Complicated Foundation The Great Valley is underlain by many NE-SW trending high displacement thrust faults and high deformed and eroded asymmetric and overturned folds. As one approaches the eastern margin of the valley, the carbonate rocks show some evidence of low-level metamorphism, the result of being located closer to the source of deformation during the Alleghenian Orogeny. It should be pointed out that although some geologists place the Great Valley within the Valley and Ridge Physiographic Province, the authors choose to set it apart as a separate province because the abundance of carbonate rocks, the low topographic relief and the intensity of deformation experienced by the rocks distinguishes it from the Valley and Ridge. Back

15 The Blue Ridge Physiographic Province is the Blue Ridge Mountains. These mountains are composed of highly deformed and metamorphosed pre-Cambrian and Cambrian rocks that have been intruded by basaltic and rhyolitic magmas. The province is also called the South Mountain Anticlinorium.South Mountain Anticlinorium Blue Ridge Back

16 An anticlinorium is a broad, regional anticlinal structure composed of lesser folds. The province extends from South Mountain on the west to Catoctin Mountain on the east with Middletown Valley being located in between. Middletown Valley is floored with meta-basalts and represents the core of the anticlinorium. To the south, erosion has exposed the billion- year basement gneisses that underlie the structure. The basement rocks are of similar radiometric age beneath all of eastern North America. From central Ohio to the Atlantic, the basement rocks are known as the Grenville Complex. South Mountain Anticlinorium Back

17 These provinces lie outside West Virginia. Although the geology of these areas will not be discussed in this presentation, their physical presence is required to complete the geographic illustration to the Atlantic Ocean. While the surface geology is seemingly simple, the subsurface geology of these provinces can be quite complex. Piedmont and Coastal Plain Back

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