Paleoshoreline

A paleoshoreline (ancient shoreline) is a shoreline that existed in the geologic past. (Paleo is from an ancient Greek word meaning "old" or "ancient".)[1] A perched coastline is an ancient (fossil) shoreline positioned above the present shoreline.

Look up palaeoshoreline in Wiktionary, the free dictionary.

Tides cause the ocean to advance and recede in a very short time scale, in most places about twice per day. Weather conditions can also cause short-term variations. Coastlines can also move by coastal erosion without a change in sea level. However, "sea level" refers to the average level over a relatively long period (years). This average sea level can advance and recede over much longer periods (thousands or millions of years), causing paleoshorelines which may be difficult to identify.

Just off the coast of parts of North America, in the last 15,000 years sea level has varied from over 100 metres (330 ft) below, to as high as 10 metres (33 ft) above its present level. That entire time, humans have lived in North America.[2]

A lake may also have a paleoshoreline.[3][4]

Paleoshorelines have also been inferred on Mars;[5][6] see Burgsvik Beds and Martian dichotomy.

Image of the Bering land bridge being inundated with rising sea level across time
Paleoshorelines illustrated: Beringia sea levels (blues) and land elevations (browns) measured in metres from 21,000 years ago to present

Scientific importance

Paleoshorelines capture valuable records of environmental change and can tell us about modern shelf ecosystems. These structures can indicate distributions of seabed features that are habitats of marine life; they may also reveal the location of coastal resources once used by humans, of archaeological significance.[7]

Examples

See also

References
  1. "paleo-". dictionary.com. Retrieved 2020-12-31.
  2. "Paleoshoreline Research".
  3. Komatsu, Goro (2001). "Paleoshoreline geomorphology of Böön Tsagaan Nuur, Tsagaan Nuur and Orog Nuur: the Valley of Lakes, Mongolia". Geomorphology. 39 (3–4): 83–98. Bibcode:2001Geomo..39...83K. doi:10.1016/S0169-555X(00)00095-7. Retrieved 2021-01-01.
  4. Egger, A.E. (December 2012). "Paleoseismology from Paleoshorelines: Combining Lidar Data and Geochronology to Resolve Displacement of Pleistocene Pluvial Shorelines along Normal Faults in the Northwestern Basin and Range". AGU Fall Meeting Abstracts. 2012. Bibcode:2012AGUFMPP11A2003E. Retrieved 2021-01-01.
  5. Ruiz, Javier (November 20, 2003). "Should Paleoshorelines of ancient Martian Oceans be close to present-day equipotential Surfaces?". Proceedings of the Third European Workshop on Exo-Astrobiology. 545: 281. Bibcode:2004ESASP.545..281R.
  6. Barrett, Katherine (June 7, 2017). "Paleoshorelines, Time capsules of the ocean's ancient shorelines". Oceanbites. Retrieved 2020-12-29.
  7. "Doggerland - The Europe That Was". Retrieved 2020-12-31.
  8. "Cascadia Subduction Zone". oregon.gov. Retrieved 2020-12-31.
  9. Ryall, Julian (19 September 2007). "Japan's Ancient Underwater "Pyramid" Mystifies Scholars". nationalgeographic.com. Retrieved 2020-12-31.

Physical geography

Bodies of water


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