Geology of the Shenandoah National Park, Virginia (Contents)

Virginia Division of Mineral Resources Bulletin 86

Geology of the Shenandoah National Park, Virginia

TABLE OF CONTENTS

Cover

Front Cover: View from Old Rag Mountain toward Stony Man on the Blue Ridge crest.

Introduction

Regional geologic setting

Stratigraphy

Precambrian rocks
   Old Rag Granite
   Pedlar Formation
Precambrian (?) rocks
   Swift Run Formation
   Catoctin Formation
Cambrian System
   Weverton Formation
   Hampton (Harpers) Formation
   Erwin (Antietam) Formation
   Triassic System
Diabase dikes
Surficial deposits

Structure

Origin of the Blue Ridge

Precambrian plutonic rocks
Late Precambrian surface
Late Precambrian volcanism
Volcanic sequence
Advance of the Cambrian sea
Paleozoic diastrophism
Mesozoic events
Carving of the mountains

Previous studies and acknowledgements

References

Glossary

Appendix: Road log along Skyline Drive

Index (omitted from the online edition)

Dark Hollow Falls during a period of peak flow in early spring. The benches that form the cascades are developed on a resistant basalt flow of the Catoctin Formation where selective weathering along gently inclined fractures has caused differential removal of the rock material at several horizons.

COMMONWEALTH OF VIRGINIA
DEPARTMENT OF PURCHASES AND SUPPLY
RICHMOND
1976

Portions of this publication may be quoted if credit is given to the Virginia Division of Mineral Resources. It is recommended that reference to this report be made in the following form:

Gathright, T. M., II, 1976, Geology of the Shenandoah National Park, Virginia: Virginia Division of Mineral Resources Bulletin 86, 93 p.

VIRGINIA DIVISION OF MINERAL RESOURCES
James L. Colver
Commissioner of Mineral Resources and State Geologist
CHARLOTTESVILLE, VIRGINIA

DEPARTMENT OF CONSERVATION AND ECONOMIC DEVELOPMENT
Richmond, Virginia

MARVIN M. SUTHERLAND, Director
JERALD F. MOORE, Deputy Director
A. S. RACHAL, JR., Executive Assistant

BOARD

FRED W. WALKER, Ashland, Chairman
MAJOR T. BENTON, Suffolk, Vice Chairman
D. HENRY ALMOND, Richmond
A. R. DUNNING, Millwood
ARTHUR P. FLIPPO, Doswell
ADOLPH U. HONKALA, Richmond
J. H. JOHNSON, West Point
FREDERIC S. REED, Manakin-Sabot
COLLINS SNYDER, Accomac
WILLIAM H. STANHAGEN, Falls Church
SHERMAN WALLACE, Cleveland
E. FLOYD YATES, SR., Powhatan

ILLUSTRATIONS

PLATE

1. Geologic map of the Shenandoah National Park, Virginia—northern section (omitted from the online edition)
2. Geologic map of the Shenandoah National Park, Virginia—central section (omitted from the online edition)
3. Geologic map of the Shenandoah National Park, Virginia—southern section (omitted from the online edition)

FIGURE

Front Cover. View from Old Rag Mountain
Frontispiece. Dark Hollow Falls
1. Location map
2. Small mountain farm
3. Rocky western ridges
4. Hawksbill from Crescent Rock
5A. Shenandoah National Park and adjacent areas from 600 miles above the earth
5B. Generalized geologic map
6. Generalized columnar section
7. Boulders on the crest of Old Rag Mountain
8. Vertical, subhorizontal, and moderately inclined joints on Old Rag Mountain
9. Greenstone dike that forms a flight of natural stairs on Old Rag Mountain
10. Gneissic hypersthene granodiorite of the Pedlar Formation at Marys Rock Tunnel
11. Granite gneiss south of Land Run Gap
12. Metabasalt ledge of the Catoctin Formation above Big Bend fire road
13. Aerial photograph of Catoctin lava flows capping Mount Marshall
14. Amygdaloidal basalt on Bucks Elbow Mountain
15. Epidotized flow breccia at Beagle Gap
16. Purple volcanic slate at Beagle Gap
17. Conglomerate bed on Turk Mountain Trail
18. Quartz-pebble conglomerate on Overall Run
19. Weverton quartzite ledge on Appalachian Trail
20. Hampton (Harpers) phyllite
21. Quartzite beds at Blackrock in the Hampton (Harpers) Formation
22. Metasandstone and phyllite of the Hampton (Harpers) Formation on Big Run
23. Erwin (Antietam) quartzite ledges and talus on Big Run
24. Skolithos in Erwin (Antietam) quartzite near Calvary Rocks
25. Erwin (Antietam) quartzite along the trail crossing Rocky Mount
26. Lichen-covered quartzite blocks at Black Rock
27. Anticline and syncline outlined by quartzite ledges
28. Strongly lineated protomylonite
29. Sawed surface of refolded mylonite
30. Brecciated Erwin (Antietam) quartzite
31. Geologic time scale
32. Late Precambrian time
33. Late Precambrian time
34. Earliest Cambrian time
35. Early Cambrian time
36. Middle and Late Cambrian time
37. Present land surface
38. Catoctin Formation at Signal Knob Overlook
39. Columnar basalt of the Catoctin Formation at Indian Run Overlook
40. Granodiorite of the Pedlar Formation at Hogback Overlook
41. North face of Old Rag Mountain
42. View from Crescent Rock Overlook
43. Amygdaloidal metabasalt
44. Porphyritic basalt
45. Phyllite and metasandstone
46. Overturned anticline
Back Cover: Columnar basalt ledge

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Last Updated: 28-Nov-2007