Скачать или смотреть REGRESSION 🌊: a

Regression in geology means a drop in sea levels, extending the shoreline further offshore. When seeing the resulting sediments from a regressive sequence, the materials tend to reflect the shallowing of the sedimentary environment and a change of the sedimentary rocks.
Far offshore, limestones form.
Closer to shore, siltstones/mydstones form.
At the sandy beach shoreline, sandstones form.
Geoscientists recognize a regressive sedimentary sequence by seeing limestone atop stiltstone/mudstone atop sandstone. If it is flipped - sandstone atop siltstone atop limestone - that indicates the shoreline was encroaching onto land (transgression).
Geologic evidence shows that seas have fluctuated up and down, causing transgressive and regressive patterns in the sedimentary rock record.
Geology Rocks!