Pocahontas Formation

Pocahontas Formation (Campbell, 1896; also mapped with Pz and Pl ). Sandstone, siltstone, shale, underclay, and coal. Sandstone, feldspathic, micaceous, dark and light lithic fragments, pale-orange, light-brownish-gray, and medium to dark-gray, very-fine- to medium-grained, fine- to coarse-grained in northern outcrop area, thin- to thick-bedded and massive, sparsely cross-bedded, ripple-marked, with local shale interbeds and dark laminations; contains well-rounded quartz pebbles as much as 1 inch in diameter, locally in channel-fill deposits and basal beds; thin-bedded sandstone contains shale interbeds, shale fragments, ironstone nodules, coal debris, and sparse plant fossils. Few quartzose sandstones commonly interbedded with thin, dark-gray shales and siltstones in subsurface in Buchanan, Dickenson, and Wise counties (Miller, 1974). Sandstone comprises 70 per cent of formation (Englund,1979). Siltstone and shale, medium- to dark-gray, laminated, even- to irregulary bedded, fissile to fl ggy, fossiliferous with fresh and brackish water animal and plant fossils (Englund, 1979). Coal, finely cleated. Underclay, medium-gray, clayey to silty, contains root casts. Basal part gradational to intertonguing with underlying Bluestone Formation of the Pennington Group; base placed at top of red, green, or gray calcareous, marine shales of the underlying Bluestone Formation (Miller, 1974). The Pocahontas wedges out in the subsurface in the northwestern parts of Lee, Wise, Dickenson, and Buchanan Counties (Englund, 1979; Miller, 1974) and is thickest in western and northern Tazewell County. It ranges from 0 to 970 feet in thickness.
State Virginia
Name Pocahontas Formation
Geologic age Pennsylvanian
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone
Sedimentary > Clastic > Siltstone
Sedimentary > Clastic > Mudstone > Shale
Minor
Sedimentary > Coal
Comments Appalachian Plateaus and Valley and Ridge
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.

NGMDB product
Counties Tazewell