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PENNSYLVANIAN GEOLOGY OF A PART OF THE SOUTHERN APPALACHIAN COAL FIELD

By
Harold R. Wanless
Harold R. Wanless
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Published:
January 01, 1946

The Pennsylvanian strata of western Virginia, southeastern Kentucky, Tennessee, and northwestern Georgia consist of shales, sandstones, siltstones, numerous coals, several conglomerates, some thin bands of ironstone, and a few limestones. There is a maximum thickness of nearly 6000 feet near Big Stone Gap, Wise County, Virginia. The strata are of early Pennsylvanian age, equivalent to the Pottsville and the lower part of the Allegheny of Pennsylvania.

The region is divided by anticlines, thrust faults and state boundaries into six or more segments where the strata have been differently named and classified. The coals of minable thickness have been named in the many mining districts in the area, and some massive cliff- or bench-forming sand-stones or conglomerates, a few thick shales, and some marine limestones have been named; most of the other lithologic units are unnamed.

Field studies permitted the correlation of many of the coals and other named beds or formations between separated areas and a general classification of the strata for the area of this report was made, as follows:

Strata of Kanawha and Lower Allegheny age

  Anderson formation, 560–950 feet

  Scott formation, 475–880 feet

  Jellico formation, 330–630 feet

  Briceville formation, 500–1800 feet

Strata of Lee (New River) age

  Corbin sandstone, 10–150 feet

  Duskin Creek shale, 50–300 feet

  Rockcastle sandstone, 40–220 feet

  Vandever shale, 30–270 feet

  Newton sandstone, 0–100 feet

  Eastland shale, 0–700? feet

  Herbert sandstone, 0–100 feet

  Whitwell shale, 10–200 feet

  Sewanee conglomerate 0–150 feet

  Gizzard formation, 0–615 feet

It is not proposed that these names, most of which are derived from Tennessee localities, should supplant the systems of nomenclature already in use in Kentucky, Virginia, and Georgia. However they serve better as a basis for comparing the successions of the several areas than do the other classifications.

It was found that there are marked changes in lithology and thicknesses of stratigraphic intervals on opposite sides of major structures such as the Sequatchie Valley anticline and the Pine Mountain thrust fault, suggesting that these structures developed along belts which suffered differential movements during early Pennsylvanian sedimentation. The strata exhibit a type of cyclical sedimentation, but details of lithology vary more between nearby localities than in the Eastern Interior and Mid-continent areas where the Pennsylvanian is classified into cyclothems which can be traced for long distances. The subdivision of this succession into cyclothems seems inadvisable at present.

The sediments are all of aqueous deposition, and probably record piedmont, delta, marsh, lake, and shallow sea-floor environments. Marine fossils are found in only about one per cent of the strata, while fossil plant remains are much more widely distributed. This suggests that the waters in which deposition took place were fresh a large part of the time. Neither marine invertebrates nor fossil plants have yet been used as a basis for fine subdivision of the stratigraphic column, although both offer promise of some usefulness for this purpose. Spores isolated from coal by maceration are also being investigated as aids in correlation. The source of sediment would seem to lie to the southeast in the old land Appalachia, because thicknesses of stratigraphic units increase and the sediments generally become coarser-grained in that direction. There is, however, some evidence suggesting the derivation of sediment from the Canadian shield to the north, the greater thickness in the southeast in that case resulting from greater downwarping rather than proximity to the source of sediment.

The paper includes descriptions of 37 stratigraphic sections representing the formational subdivisions in the several districts in which different systems of nomenclature are used. It is illustrated with 20 cross-section diagrams, showing the nature of stratigraphic variation between outcrops along selected lines paralleling and transverse to the regional strike.

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Contents

GSA Memoirs

Pennsylvanian Geology of a Part of the Southern Appalachian Coal Field

Harold R. Wanless
Harold R. Wanless
Search for other works by this author on:
Geological Society of America
Volume
13
ISBN print:
9780813710136
Publication date:
January 01, 1946

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