Syncline

{{Short description|Geological fold}} thumb|A syncline is a fold of rocks with younger rock layers closer to the center of the structure, whereas an anticline is the inverse of a syncline.|right|upright=1.95 In structural geology, a '''syncline''' is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A '''synclinorium''' (plural '''synclinoriums''' or '''synclinoria''') is a large syncline with superimposed smaller folds.<ref>Synclinorium. (2008). In Encyclopædia Britannica. Retrieved May 03, 2008, from Encyclopædia Britannica Online: http://www.britannica.com/EBchecked/topic/578375/synclinorium</ref> Synclines are typically a downward fold ('''synform'''), termed a synformal syncline (i.e. a trough), but synclines that point upwards can be found when strata have been overturned and folded (an antiformal syncline).

==Characteristics== On a geologic map, synclines are recognized as a sequence of rock layers, with the youngest at the fold's center or ''hinge'' and with a reverse sequence of the same rock layers on the opposite side of the hinge. If the fold pattern is circular or elongate, the structure is a basin. Folds typically form during crustal deformation as the result of compression that accompanies orogenic mountain building.

==Notable examples== * Powder River Basin, Wyoming, US * Sideling Hill roadcut along Interstate 68 in western Maryland, US, where the Rockwell Formation and overlying Purslane Sandstone are exposed * Forêt de Saou syncline in Saou, France * Southland Syncline in the southeastern corner of the South Island of New Zealand, including The Catlins and the Hokonui Hills * Strathmore Syncline, Scotland * Wilpena Pound, Flinders Ranges, South Australia * Fort Valley, Shenandoah County, Virginia * Hondo Syncline in the Picuris Mountains of New Mexico, an example of an overturned syncline<ref>{{cite journal |last1=Bauer |first1=Paul W. |last2=Williams |first2=Michael L. |title=Stratigraphic nomenclature ol proterozoic rocks, northern New Mexico-revisions, redefinitions, and formalization. |journal=New Mexico Geology |date=August 1989 |volume=11 |issue=3 |pages=45–52 |doi=10.58799/NMG-v11n3.45 |url=https://geoinfo.nmt.edu/publications/periodicals/nmg/11/n3/nmg_v11_n3_p45.pdf |accessdate=15 April 2020}}</ref> *Afikpo syncline, Nigeria * Table Mountain, South Africa

==Gallery== <gallery> File:Sideling Hill cut MD1.jpg|Syncline exposed in Sideling Hill roadcut File:Provo Canyon syncline.jpg|Snow-dusted syncline in Provo Canyon, Utah File:Syncline.JPG|Road cut near Fort Davis, Texas showing a syncline File:Rainbow Basin.JPG|Rainbow Basin Syncline in the Barstow Formation near Barstow, California File:SynclineCalico.JPG|Syncline in the lower parking lot of Calico Ghost Town; the ductile folding is at the base and the brittle is above. File:Roundtop Hill outcrop1.jpg|Synclinal fold in Silurian Wills Creek Formation or Bloomsburg Formation at Roundtop Hill (Maryland) File:Bear Valley east wall.jpg|East wall of Bear Valley Strip Mine, near Shamokin, Pennsylvania File:Upheaval Syncline campsite.jpg|Syncline in Navajo Sandstone, Upheaval Dome, Canyonlands National Park, Utah File:The Catlins.jpg|Satellite view of part of New Zealand's Southland Syncline, showing parallel folds running northwest–southeast File:Wilpena Pound - Aerial View.jpg|Wilpena Pound, a synclinal basin in the Flinders Ranges of South Australia </gallery>

==References== {{Reflist}}

Category:Structural geology