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If the angle between the limbs is large (70–120 degrees), then the fold is an "open" fold, but if the angle between the limbs is small (30 degrees or less), then the fold is a "tight" fold. [4] If an anticline plunges (i.e., the anticline crest is inclined to the Earth's surface), it will form Vs on a geologic map view that point in the ...
When the limbs of a fold converge upward, the fold is referred to as an antiform. Conversely, when the limbs of a fold converge downward, the fold is known as a synform. Not to be confused with these terms (antiform and synform), the terms anticline and syncline are used in the description of the stratigraphic significance of the fold.
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
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. 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 fold axis "is the closest approximation to a straight line that when moved parallel to itself, generates the form of the fold". [2] (Ramsay 1967). A fold that can be generated by a fold axis is called a cylindrical fold. This term has been broadened to include near-cylindrical folds. Often, the fold axis is the same as the hinge line. [3] [4]
See the main article on folds for a fuller treatment of fold types and nomenclature but in brief, an anticline is an arch-like fold whereas a syncline is its converse; a downfold. Antiforms , anticlinoria , synforms and synclinoria are variations on these.
A river anticline is a geologic structure that is formed by the focused uplift of rock caused by high erosion rates from large rivers relative to the surrounding areas. [1] An anticline is a fold that is concave down, whose limbs are dipping away from its axis, and whose oldest units are in the middle of the fold. [ 2 ]
If some of the units in the fold are facing downward, the structure is called an overturned anticline or syncline, and if all of the rock units are overturned or the correct up-direction is unknown, they are simply called by the most general terms, antiforms, and synforms. A diagram of folds, indicating an anticline and a syncline