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Very small cross-lamination means that the ripple height is roughly one centimeter. It is lenticular, wavy and flaser lamination. Small Small cross-bedding are ripples set at a height less than ten centimeters, while the thickness is only a few millimeters. Some ripples that may fit this category are wind ripples, wave ripples, and current ripples.
Cross-bedded sediments are recognized in the field by the many layers of "foresets", which are the series of layers that form on the downstream or lee side of the bedform (ripple or dune). These foresets are individually differentiable because of small-scale separation between layers of material of different sizes and densities.
Asymmetrical ripple marks These are created by a one way current, for example in a river, or the wind in a desert. This creates ripple marks with still pointed crests and rounded troughs, but which are inclined more strongly in the direction of the current. For this reason, they can be used as palaeocurrent indicators.
As grains settle out, current ripples develop, with climbing ripples developing if sedimentation rates are high enough. If shear is imposed on the ripple beds by an earthquake and/or by an overlying turbidite/turbidity current, the ripple laminations can be deformed into convolute laminations and flame structures.
Cross-bedding – the axis of a trough cross bed or the down-dip direction of a tabular cross bed point the direction of paleo flow. Current ripple marks – will have the short side of the ripple pointing down stream. Sole markings/flute casts – the short, steep side will point up stream, and the long, tapered side points down stream.
Flaser bedding, vertical cross section. If the amount of deposited sand exceeds mud deposits, we get ripples with isolated mud drapes in ripple troughs and crests. This type of sedimentary structure is called flaser bedding. Flaser bedding can be subdivided according to how the mud is deposited over the rippled sand.
In geology, lamination (from Latin lāmina 'thin layer') is a small-scale sequence of fine layers (pl.: laminae; sg.: lamina) that occurs in sedimentary rocks. Laminae are normally smaller and less pronounced than bedding .
Types of beds include cross-beds and graded beds. Cross-beds, or "sets," are not layered horizontally and are formed by a combination of local deposition on the inclined surfaces of ripples or dunes, and local erosion. Graded beds show a gradual change in grain or clast sizes from one side of the bed to the other. A normal grading occurs where ...