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¡ 58.944Õ North, 82¡ 27.846Õ West).
Cross bedding in tilted quartzose sandstones of the Dakota Group (Albian Stage,
upper Lower Cretaceous) at Dinosaur Ridge, west of Denver, Colorado, USA.