Transgression and Regression

In the study of sequency stratigraphy, some elemental concepts must be known. In this case the geologic terms 'transgression' and 'regression' are referred to the changes that the sea level has experimented through geologic history and its sedimentary consequences. A geologist studies this rising and droping of sea level, analyzing the sediments occurred during this events.

Obviously, depending on the size of the sediments carried by currents and washings of the shore and land, and the energy of these processes, the sediments as sand or mud will be deposited on the sea bed as the energy from shore to offshore decreases, being the heaviest (coarse sediment) deposited nearer of the shore than the lightest sediments (fine grain).

Simplifying we could say that a transgression corresponds with  a rising of sea level, and regression is a droping of sea level. However to identify these events in a stratigraphic column, we should know what is the typical facies configuration.

Below this simple and very easy video shows the processes in a general way, that can be even more complicated to identify in a realistic case.

Care must be taken when the limestone are presented at the bottom of the sequence, which could be a general case. I would say that (in my opinion) carbonates generation is a subject to be treated apart, as it depends on if the source of them is available (biogenic generation), so temperatures, shallow waters,...

Anyway thanks to Patrick Baldwin for this material.