syncline

geology

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July 14, 2026

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Stratification Stratification of sedimentary rock on the Rainbow Basin syncline near Barstow, Calif., U.S.

A syncline is a geological term describing a trough in stratified rock where the beds dip inward from both sides. This is the opposite of an anticline, which is convex upward. Synclines are a type of fold, which are undulations or waves in the Earth's crust. These folds form when stratified rocks, originally deposited in flat layers, are warped by compressional forces.12

While the term "geosyncline" was once used to describe large troughs where sediment accumulated and subsequently folded into mountains, modern geology often explains these formations through plate tectonics.3

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mountain
Alpine- (or Himalayan-)type belts
…regularly spaced folds—alternating anticlines and synclines—and thrust on top of one another. The Valley and Ridge province of Pennsylvania, which was formed during the collision of Africa and North America near the end of Paleozoic time (about 240,000,000 years ago), is a classic example.
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…regularly spaced folds—alternating anticlines and synclines—and thrust on top of one another. The Valley and Ridge province of Pennsylvania, which was formed during the collision of Africa and North America near the end of Paleozoic time (about 240,000,000 years ago), is a classic example.
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salt dome
Physical characteristics of salt domes.
…dip down into the surrounding synclines. The domed strata are generally broken by faults that radiate out from the salt on circular domes but that may be more linear on elongate domes or anticlines with one fault or set of faults predominant. Lowered strata develop into synclines, and a circular…
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…dip down into the surrounding synclines. The domed strata are generally broken by faults that radiate out from the salt on circular domes but that may be more linear on elongate domes or anticlines with one fault or set of faults predominant. Lowered strata develop into synclines, and a circular…
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fold
…is convex upward, and a syncline is a fold that is concave upward. An anticlinorium is a large anticline on which minor folds are superimposed, and a synclinorium is a large syncline on which minor folds are superimposed. A symmetrical fold is one in which the axial plane is vertical.…
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…is convex upward, and a syncline is a fold that is concave upward. An anticlinorium is a large anticline on which minor folds are superimposed, and a synclinorium is a large syncline on which minor folds are superimposed. A symmetrical fold is one in which the axial plane is vertical.…
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