CROSS  BEDDING

 

Cross beds and cross laminations (a.k.a. cross stratification) are tilted sedimentary layers between horizontal layers.  They form in one-directional currents by wind or water.

 

Many names for different types of cross stratification are available, depending on the specific geometry of the sedimentary structure.  These include angular cross bedding, tabular cross bedding (planar cross bedding), tangential cross bedding, trough cross bedding (festoon cross bedding), herringbone cross bedding, hummocky cross bedding, swaley cross bedding, climbing ripples cross bedding (ripple cross bedding), contorted cross bedding, overturned cross bedding (recumbently folded cross bedding; prolapsed cross bedding), etc.

 


 

Tangential cross bedding in quartzose sandstones of the Allegheny Group (Desmoinesian, Middle Pennsylvanian).  Some have geometries transitional into angular cross bedding.  The original current direction was from right to left (<<<<<<<).

Locality: roadcut along the eastern side of Smokey Hollow Road, eastern side of Kyger Run, eastern Bloomfield Township, southeastern Jackson County, southern Ohio, USA (38 58.944 North, 82 27.846 West).

 


 

Cross bedding in tilted quartzose sandstones of the Dakota Group (Albian Stage, upper Lower Cretaceous) at Dinosaur Ridge, west of Denver, Colorado, USA.

 


 

 

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