Slump Structures

Slump structures typically form in mudstone and sandy mudstone beds that were rapidly deposited.  Deformation results shortly after deposition, by the movement of unconsolidated (or semiconsolidated) sediments, primarily under the influence of gravity.   Beds that display soft-sediment deformation can usually be distinguished from tectonically deformed beds by the presence of undisturbed layers above and/or below the deformed horizons.

	Pigeon Point Formation, north-central California.  Undeformed laminae above and below the deformed sand and shale beds in the center of the photo.
	Convolute Lamination.  Plage Victor, Quebec.  Undeformed laminae below are overlain by deformed laminae in upper part of bed.
	Convolute  Lamination.  ???  Larger-scale deformational effects, bordering on load structure or, if deformation had continued, this example might have progressed to ball-and-pillow structure.
	Kingston Peak Formation, southeastern California.  Note the deformed beds near the center of the photo, overlain by undeformed beds in the upper part of the photo (under the scale).