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An arrowed line showing where rock has been bent.
Also known as: Anticline symbol, Syncline symbol
A fold axis is drawn as a line with arrows showing whether the fold arches up or troughs down, and whether the axis itself plunges. Antiforms and synforms are drawn with opposed arrows, so the direction of two small arrowheads distinguishes an upfold from a downfold.
Marks the axis of a fold in rock strata, with arrows distinguishing an upward-arching antiform from a downward-troughing synform.
Contexts: Technical drawing, Maps
Adds a plunge arrow where the axis is not horizontal, since a fold axis can itself be tilted along its length.
Contexts: Technical drawing, Maps
A line following the crest of a fold with small paired arrows attached, pointing either outwards or inwards.