Fractures of the Appalachian Mountains

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This photograph shows edge fringe cracks propagating downward into a thick shale from a parent joint in a siltstone bed. The parent joint, striking 342¡, is typical of early dip joints that propagated during layer-parallel shortening of the Appalachian Plateau detachment sheet. The fringe cracks, striking 351¡, are consistent with a clockwise stress field rotation accompanying the Alleghanian Orogeny in both the Appalachian Plateau and Valley and Ridge.


This example of joint development has appeared in several publications including

Engelder (1985) Journal of Structural Geology
Pollard and Aydin (1988) Geological Society of America Bulletin
Helgeson and Aydin (1991) Journal of Structural Geology
Engelder (1993) Stress Regimes in the Lithosphere
Davis and Reynolds (1996) Structural Geology


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