Formation of Cross Beds When a depositional environment has sand in it and water or air moves the sand grains around, those grains can build up into piles of sediment. The result is a rock that has a base portion which shows the run out of the avalanching grains and a top that is truncated by the next bedding plane. STRATIFICATION refers to the way sediment layers are stacked over each other, and can occur on the scale of hundreds of meters, and down to submillimeter scale. CROSS-BEDDING is a feature that occurs at various scales, and is observed in conglomerates and sandstones. These tilted layers contained within larger layers are termed cross bedding. If you go dig trenches into modern sediments, you will find that cross-beds form a part of ripples and dunes.
Cross bedding definition, having irregular laminations, as strata of sandstone, inclining in various directions not coincident with the general stratification. (geology) layering within one or more beds in a series of rock strata that does not run parallel to the plane of stratification Also called false bedding. Define cross bedding. cross bedding synonyms, cross bedding pronunciation, cross bedding translation, English dictionary definition of cross bedding. N geology layering within one or more beds in a series of rock strata that does not run parallel to the plane of stratification. Planar Laminae are parallel to bedding, e.g. planar.
Wedge bedding. Successive stack of erosive-based channels creates wedge-shaped bedding cross-sections. Shiguai Formation, Inner Mongolia, China. Structure of ripples: Grain Avalanches down lee slopes result in small scale cross lamination. Sections normal to flow may be horizontal, defining planar cross lamination (2-D ripples) or may be trough-shaped, defining trough cross lamination (3-D ripples). 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. These plane beds produce well-defined planar lamination with laminae that are typically 5 20 grains thick.
Straight crested dunes produce planar cross beds. Sinuous and lenticular dunes produce trough cross beds. Get information, facts, and pictures about Bedding at Encyclopedia.com. World of Earth Science A Dictionary of Earth Sciences The Oxford Pocket Dictionary. The bottom surface of a stratum roughly conforms to irregularities of the underlying surface; the stratification plane above the stratum, however, tends to be nearly horizontal. These are cross-bedding, which is common in fluvial or eolian deposits, and graded bedding, which reflects transport by density (or turbidity) currents or, in certain cases, varved deposits. The definition of cross bedding in the dictionary is layering within one or more beds in a series of rock strata that does not run parallel to the plane of stratification Also called: false bedding. Includes plane bedding and cross-bedding. Secondary sedimentary structures: are caused by post-depositional processes, including biogenic, chemical, and mechanical disruption of sediment. Planar bedding develops as wave after wave of ocean water distributes river-derived sand grains across the beach (aggradational stacking).