Planar Tabular Cross Bedding Sample Plans PDF

Tabular (planar) cross-beds consist of cross-bedded units that are large in horizontal extent relative to set thickness and that have essentially planar bounding surfaces. Tabular cross-bedding. These steep foresets are typical of eolian deposition. Late Jurassic, Liaoning Province, China. Trough cross-bedding. Trough cross bedding is produced by the downflow migration of lunate dunes in both subaqueous and subaerial environments. Beach and Longshore Bar Cross-bedding. Upper plane bed results in planar stratification. Multiple sets of dune foresets forming tabular cross-stratification.

planar tabular cross bedding 2These tilted layers contained within larger layers are termed cross bedding. Photo taken near New Kensington, PA These matched sets of cross-beds tilting in opposite directions are called herringbone cross-beds. This is planar cross-bedding and the surface at the bottom of the cross-beds is flat and close to horizontal because of the absence of scouring in the trough. Cross-beds bound by horizontal surfaces are sometimes referred to as tabular cross-bedding. See: trough cross stratification and other examples at: dune cross stratification See ripple cross lamination on Mars: martian ripples.

The dominant channel bedforms are dunes, which deposit trough cross bedding. Cross-channel bars deposit large sets of planar tabular cross bedding. Photo by W. W. Little Planar (tabular) Cross-bedding Planar cross-bedding flattens little or none toward the base in longitudinal profile and forms apparent planar bedding in transverse sections.

Cross Bedding

planar tabular cross bedding 3

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