progradation

{{short description|Growth of a river delta into the sea over time}}

In sedimentary geology and geomorphology, the term progradation refers to the growth of a river delta farther out into the sea over time. This occurs when the volume of incoming sediment is greater than the volume of the delta that is lost through subsidence, sea-level rise, or erosion.{{cite book |editor1-last=Jackson |editor1-first=Julia A. |title=Glossary of geology. |date=1997 |publisher=American Geological Institute |location=Alexandria, Virginia |isbn=0922152349 |edition=Fourth |chapter=progradation}}

Progradation can be caused by:

• Periods of sea-level fall which result in marine regression. This can occur during major continental glaciations within ice ages,{{cite journal |last1=Schofield |first1=J. C. |title=Sea-level fluctuations cause periodic, post-glacial progradation, South Kaipara Barrier, North Island, New Zealand |journal=New Zealand Journal of Geology and Geophysics |date=March 1975 |volume=18 |issue=2 |pages=295–316 |doi=10.1080/00288306.1975.10418201|bibcode=1975NZJGG..18..295S }} be caused by changes in the rates of seafloor spreading that affects the volume of the ocean basins,{{cite book |last1=Embry |first1=Ashton F. |title=Sea-level changes : an integrated approach |date=1988 |publisher=Society of Economic Paleontologists and Mineralogists |location=Tulsa, Okla. |isbn=0918985749 |url=https://archives.datapages.com/data/sepm_sp/SP42/Triassic_Sea-Level_Changes.htm |access-date=23 May 2022 |chapter=Triassic sea-level changes: Evidence from the Canadian Arctic Archipelago}} or tectonic effects on the regional mantle density structure that can change the geoid elevation.{{cite journal |last1=Stoker |first1=Martyn S. |last2=Holford |first2=Simon P. |last3=Hillis |first3=Richard R. |last4=Green |first4=Paul F. |last5=Duddy |first5=Ian R. |title=Cenozoic post-rift sedimentation off northwest Britain: Recording the detritus of episodic uplift on a passive continental margin |journal=Geology |date=July 2010 |volume=38 |issue=7 |pages=595–598 |doi=10.1130/G30881.1|bibcode=2010Geo....38..595S |url=http://nora.nerc.ac.uk/id/eprint/9879/1/Stoker_et_al_2010_Geology.pdf }}
• Extremely high sediment input, such as by the Huang He (Yellow River) in China, which drains the Loess plateau,{{cite journal |last1=Saito |first1=Yoshiki |last2=Wei |first2=Helong |last3=Zhou |first3=Yongqing |last4=Nishimura |first4=Akira |last5=Sato |first5=Yoshio |last6=Yokota |first6=Setsuya |title=Delta progradation and chenier formation in the Huanghe (Yellow River) delta, China |journal=Journal of Asian Earth Sciences |date=August 2000 |volume=18 |issue=4 |pages=489–497 |doi=10.1016/S1367-9120(99)00080-2|bibcode=2000JAESc..18..489S }} or from high sediment loads in proglacial rivers.{{cite journal |last1=Nemec |first1=W. |last2=LφNNE |first2=Ida |last3=Blikra |first3=Lars H. |title=The Kregnes moraine in Gauldalen, west-central Norway: anatomy of a Younger Dryas proglacial delta in a palaeofjord basin* |journal=Boreas |date=16 January 2008 |volume=28 |issue=4 |pages=454–476 |doi=10.1111/j.1502-3885.1999.tb00234.x|s2cid=128823562 }}