Retrogradation

This article is about the geological term related to river deltas. For other uses, see Retrograde (disambiguation).

Retrogradation is the landward change in position of the front of a river delta with time. This occurs when the mass balance of sediment into the delta is such that the volume of incoming sediment is less than the volume of the delta that is lost through subsidence, sea-level rise, and/or erosion. As a result, retrogradation is most common:

• during periods of sea-level rise which results in marine transgression. This can occur during major periods of global warming and the melting of continental ice sheets.
• with extremely low sediment input.

See also

• Progradation – Growth of a river delta into the sea over time
• River delta – Silt deposition landform at the mouth of a river
• Aggradation – Increase in land elevation due to the deposition of sediment
• Marine transgression – Geologic event in which sea level rises relative to the land
• Marine regression – Geologic event in which sea level falls relative to the land
• Sedimentology – Study of natural sediments and their formation processes
• Stratigraphy – Study of rock layers and their formation
• Sequence stratigraphy – Study and analysis of groups of sedimentary deposits
• Sediment transport – Movement of solid particles, typically by gravity and fluid entrainment

References

Schlumberger Oilfield Glossary