Graded bedding

Graded bedding is a sorting of particles according to clast size and shape on a lithified horizontal plane.

Density and gravity forces in the downward movement of these materials in a confined system result in a separating of the detritus settling with respect to size.

Nicholas Steno first published his hypothesis in 1669 after recognizing that fossils were preserved in layers of rock (strata).

[6] Note: The secondary processes of compaction, cementation, and lithification help to hold a stratified bed in place.

[6] In aeolian or fluid depositional environments, where there is a decrease in transport energy over time, the bedding material is sorted more uniformly, according to the normal grading scale.

Thus, graded beds form at points with decreased slopes in wide areas with less bounding of energy current flows.

[7] Changes in currents or physical deformation in the environment can be determined upon observation and monitoring of a depositional surface or lithologic sequence with unconformities above or below a graded bed.

Detrital sedimentary graded beds are formed from erosional, depositional, and weathering forces.

Organic sedimentation of parent material from decaying plant matter in bogs or swamps can also result in a graded bedding complex.