structural geology Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover informati ...

, a syncline is a fold with younger layers closer to the center of the structure, whereas an

anticline In structural geology, an anticline is a type of Fold (geology), fold that is an arch-like shape and has its oldest Bed (geology), beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex curve, c ...

is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed smaller folds. 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 Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

, US *

Sideling Hill Sideling Hill, also Side Long Hill, is a long, steep, narrow mountain ridge in the Ridge-and-valley Appalachians, Ridge-and-Valley (or Allegheny Mountains) physiographic province of the Appalachian Mountains, located in Washington County, Maryla ...

roadcut along

Interstate 68 Interstate 68 (I-68) is a Interstate Highway in the U.S. states of West Virginia and Maryland, connecting Interstate 79, I-79 in Morgantown, West Virginia, east to Interstate 70, I-70 in Hancock, Maryland. I-68 is also Corridor E of ...

in western

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

, US, where the Rockwell Formation and overlying Purslane Sandstone are exposed * Forêt de Saou syncline in Saou, France *

Southland Syncline The Southland Syncline is a major geological structure located in the Southland, New Zealand, Southland Region of New Zealand's South Island. The syncline folds the Mesozoic Greywacke, greywackes of the Stratigraphy of New Zealand, Murihiku Terr ...

in the southeastern corner of the

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

of New Zealand, including

The Catlins The Catlins (sometimes referred to as The Catlins Coast) comprise an area in the southeastern corner of the South Island of New Zealand. The area lies between Balclutha, New Zealand, Balclutha and Invercargill, straddling the boundary between ...

and the Hokonui Hills * Strathmore Syncline, Scotland *

Wilpena Pound Wilpena Pound ("Ikara" in the Adnyamathanha language) is a major natural amphitheatre of mountains located north of Adelaide, South Australia, Australia in the heart of the Ikara-Flinders Ranges National Park. Its fringe is accessible by a sea ...

, Flinders Ranges,

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

* Fort Valley, Shenandoah County, Virginia * Hondo Syncline in the Picuris Mountains of

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

, an example of an overturned syncline * Afikpo syncline, Nigeria

Gallery

File:Sideling Hill cut MD1.jpg, Syncline exposed in

roadcut File:Provo Canyon syncline.jpg, Snow-dusted syncline in Provo Canyon,

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

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 Barstow is a city in San Bernardino County, California, in the Mojave Desert of Southern California. Located in the Inland Empire region of California, the population was 25,415 at the 2020 United States census, 2020 census. Barstow is an impor ...

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 The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

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 Shamokin - (; Saponi Algonquian languages, Algonquian ''Schahamokink'', meaning "place of eels") (Unami language, Lenape Indian language: Shahëmokink) is a city in Northumberland County, Pennsylvania, United States. Surrounded by Coal Township ...

File:Upheaval Syncline campsite.jpg, Syncline in Navajo Sandstone, Upheaval Dome,

Canyonlands National Park Canyonlands National Park is a national park of the United States located in southeastern Utah near the town of Moab. The park preserves a colorful landscape eroded into numerous canyons, mesas, and buttes by the Colorado River, the Green Rive ...

, Utah File:The Catlins.jpg, Satellite view of part of New Zealand's

, showing parallel folds running northwest–southeast File:Wilpena Pound - Aerial View.jpg,

, a synclinal basin in the Flinders Ranges of South Australia

References

Structural geology {{struct-geology-stub

Characteristics

Notable examples

Gallery

See also

References