Interbedding

[2] Intercalation is a special case of interbedding where a layer is variably inserted into an already existing sequence; or where two separate depositional environments in close spatial proximity migrate alternately across the contact.

For example intercalated conglomerate and sandstone looks like ripples of different material networked through each other somewhat off the horizontal, as the beds are deposited in a gradient.

This is likely due to differing fluvial conditions and gradual changes in sediment transport over time.

In its most conspicuous form, such an interbedding as seen on a quarry wall can look like the stripes of a zebra: a dark gray marl layer, for example twenty centimeters thick, is followed by a half-meter-thick light limestone bench, which in turn is overlaid by a marl layer and this again by limestone and so on.

Lime-marl interbeddings represent the cyclical detachment of a high carbonate production due to the stronger influence of the terrestrial background sedimentation, which is usually attributed sedimentologically to an increase in sea depth and distance from the coast at the time of deposition at the corresponding deposit location.

Interbedded graywacke - siltstone - slate in the Precambrian of Minnesota , USA. This is an outcrop of slightly metamorphosed rock that was smoothed and striated by glaciers during the Pleistocene Ice Age .
Folded sedimentary rocks (calcareous turbidite sequence) of Lower Carbonferous (Brigantian/Visean) age at Loughshinny , eastern coast of Ireland. The Variscan orogeny is responsible for the folding.