Syncline

A syncline is a geological fold in which rock layers curve downward toward the center. Its core typically contains the youngest strata.

Anticline: An upward-arching geological fold whose limbs dip away from its crest. Its upward arch contrasts with the syncline’s downward-curving form.
Stratigraphy: The study of rock layers, their sequence, distribution, and relationships. Stratigraphic order establishes which beds are youngest in a syncline’s core.
Geological map: A map showing the distribution, age, and structure of rocks at Earth’s surface. Closing or parallel map patterns can reveal a syncline’s trace and plunge.
Antiform: A fold that arches upward, regardless of the age of rocks at its core. Unlike a syncline, an antiform is defined by shape rather than stratigraphic age.
Fold (geology): A bend in originally planar rock layers produced by deformation. A syncline is one downward-curving geometry within the broader class of folds.
Bedding (geology): The layering of sedimentary or volcanic rocks formed as distinct beds. Synclines are recognized by the way originally layered rocks bend.
Cross section (geology): A vertical diagram showing geological structures beneath a line on a map. A cross section makes the syncline’s downward curvature visible below ground.
Synform: A downward-curving fold whose core’s relative rock ages are unknown or unspecified. Synform names the geometry when the youngest strata at the core cannot be established.
Fold axis: A line connecting points of maximum curvature along a geological fold. Its orientation helps describe the syncline’s shape and map pattern.
Dip (geology): The angle and direction at which a planar geological surface inclines. Beds on opposing limbs dip inward toward a typical syncline’s hinge.

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Fold mountainsBroader topic: Synclines commonly alternate with anticlines in folded strata.