WVGES

West Virginia Geology:
Feature Article


Dividing Line

In order to display the broad scope and variety of the Mountain State's geology, from time to time the West Virginia Geological and Economic Survey (WVGES) showcases articles from professional geologists not directly affiliated with the WVGES.

The Smoke Hole Region
of
West Virginia

by
Roy S. Sites
(Biographical Sketch)

The Smoke Hole region (locally known as the Smoke Holes) represents approximately 40-square miles of the Spruce Knob-Seneca Rocks National Recreational Area within the Monongahela National Forest. This area is a somewhat isolated, inaccessible, rugged mountainous-canyon region in Grant and Pendleton counties. Cave Mountain is the topographic and structural backbone of the Smoke Holes. The Smoke Holes are dissected by the pirated South Branch of the Potomac River, which flows north-northeastward through a narrow gorge for the entire length of the region, thus the term Smoke Hole Canyon or Smoke Hole Gorge. North Fork Mountain and Middle Mountain are the two prominent topographic features that form, respectively, the western and eastern boundaries of the Smoke Holes.

The geology of the Smoke Holes is dominated by the Cave Mountain anticline. The stratigraphic column exposed in this region contains Lower Silurian to Middle Devonian sandstones, limestones, and shales. This package of rocks is bounded on the lower and upper ends by two fairly competent sandstones: the Silurian Tuscarora and the Devonian Oriskany, respectively. The anticline trends N 34 degrees E, and is faulted along the southeast-dipping Cave Mountain thrust against the southeast limb of the Wills Mountain anticline (North Fork Mountain). The Cave Mountain anticline is asymmetric to the northwest with a slightly overturned northwest limb. Adjacent to this northwest limb is a highly folded and faulted zone that is representative of the designated Blue Rock synclinal "shear zone" complex of macroscale structures between the Cave Mountain and the Wills Mountain anticlines. Furthermore, the Cave Mountain anticline is a doubly-plunging fold showing a culmination at the Lower Silurian strata level near Big Bend in the center of the Smoke Holes. The anticline appears to divide into several plunging folds upsection, at the Lower Devonian strata level, toward each end of the fold. Particularly noticeable are the numerous plunging anticlinal noses at the northeastern end of the Smoke Holes.

The Cave Mountain anticline consists of subparallel northeast-trending folds and southeast-dipping thrust faults with a maximum stratigraphic displacement of approximately 1900 feet, throwing Lower Silurian rocks against Lower Devonian rocks. The Cave Mountain anticline is further structurally bounded to the northeast and southwest by major cross-strike structural discontinuities: the nearly east-west trending Petersburg lineament and an extension of the northwest-southeast trending Parsons lineament, respectively.

Overall, this region reveals the interior of this thrusted anticlinal-synclinal structure and presents a phenonmenal exposure of complex central Appalachian macroscale structures involving the Silurian-Devonian package of rocks. Geologically, the Smoke Holes are the most uniquely exposed region within the westernmost central Appalachians and they have served as a surface model for complex subsurface structures shown and/or suspected by seismic and exploratory drilling. Furthermore, this region provides detailed insight into the lowermost roof-sequence cover above the suspected duplex of Cambrian-Ordovician horse-blocks and blind-thrusts at depth.

Index Map for Block Relief Diagram of the Smoke Holes and Surrouning Region

Block Relief Diagram of the Smoke Holes and Surrounding Region

Isometric Relief Map of the Smoke Hole Region
Larger Version of the Isometric Relief Map (197K GIF, 485 pixels wide x 698 pixels high)

Major Drainage and Topographic Patterns of the Smoke Hole Region

Stratigraphic Columnar Section of the Smoke Hole Region

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Generalized Geologic Map of the Smoke Hole Region

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Cross Section C to C' of the Smoke Hole Region

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Cross Section B to B' of the Smoke Hole Region

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Cross Section A to A' of the Smoke Hole Region

Smoke Hole 'Shear Zone'


MAP OF SMOKE HOLE REGION

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Clickable Image Map of the Smoke Hole Region


Further Reading

Fold Development in the Cover Enveloping the Broadtop Horse:
G.W. Adamson, 1992, 120 p., M.S. Thesis, West Virginia University.

Geology of the Smoke Hole Region in Grant and Pendleton Counties, West Virginia:
R.S. Sites, 1971, v. 1 and 2, 106 p., M.S. Thesis, West Virginia University.

Geology of the Smoke Hole Region of West Virginia:
R.S. Sites, 1973, v. 15, p. 153-167, Southeastern Geology.

Mineral and Grant Counties:
D.B. Reger and R.C. Tucker, 1924, 866 p., includes maps, West Virginia Geological and Economic Survey County Geologic Report.

Pendleton County Geological Report:
J.L. Tilton, W.F. Prouty, and P.H. Price, 1927, 384 p., includes maps, West Virginia Geological Survey.

The Role of Macroscale Thrusts in the Deformation of the Alleghanian Roof Sequence in the Central Appalachians: A Re-evaluation:
W.M. Dunne, 1996, v. 296, p. 549-575, American Journal of Science.

Structural Analysis of the Petersburg Lineament, Central Appalachians:
R.S. Sites, 1978, 273 p., Ph.D. Dissertation, West Virginia University.

Structural Analysis of the Silurian-Devonian Cover in the Smoke Holes, West Virginia:
S.S. Gerritsen, 1988, 196 p., M.S. Thesis, West Virginia University.

The Structural Development and Deformation of the Allegheny Frontal Zone and Wills Mountain Anticlinorium - The Central Eastern Overthrust Belt:
R.A. Drabish and R.S. Sites, 1982, 108 p., Appalachian Geological Society Fifthieth Anniversary Field Trip Guidebook.

The Structural Development of the Nittany Anticlinorium in Pendleton County, West Virginia:
W.J. Perry, Jr., 1971, 227 p., Ph.D. Dissertation, Yale University.

The Wills Mountain Anticline: A Study in Complex Folding and Faulting in Eastern West Virginia:
W.J. Perry, Jr., 1978, 29 p., West Virginia Geological and Economic Survey Report of Investigation RI-32.

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Page last revised: November 10, 2005