A rock layer that has a progressive change in particle size from top to bottom. Most common is a sequence with coarse grains at the bottom and fining upwards, which is typically caused by a declining current velocity within the depositional environment.
bed in which the coarsest particles are concentrated at the bottom and grade gradually upward into fine silt, the whole bed having been deposited by a waning current.
A type of bedding in which each layer is characterized by a progressive decrease in grain size from the bottom of the bed to the top.
Rapid sedimentation leaving a distinctive texture of coarse grains followed by fine grains in a single layer. See Rhythmites.
Bedding in which internally the sediment shows a vertical gradual and progressive change in particle or grain-size. "Normal grading" is most common in which the particle size "fines-upwards", and frequently forms as a result of a gradually waning sediment-laden current, depositing progressively finer material as the current velocity decreases.
An arrangement of PARTICLE SIZES within a single bed, with coarse grains at the bottom of the bed and progressively finer grains toward the top of the bed.
The arrangement of the particles in a sediment, with larger ones at the base, passing gradually upwards into finer grain sizes.
In geology, a graded bed is one characterized by coarse sediments at its base, which grade upward into progressively finer ones. They are perhaps best represented in turbidite strata, where they indicate a sudden strong current that deposits heavy, coarse sediments first, with finer ones following as the current weakens. They can also form in terrestrial stream deposits.