The hinge surface traces of some types of folds cannot be portrayed adequately on maps using traditional symbology. Specifically, there are no widely accepted symbols suitable for hinge surfaces of (1) box folds (a class of polyclinal folds with two hinges), (2) folds whose limbs both dip in the same direction, or (3) overturned folds whose limbs dip in opposite directions. The latter two cases are not uncommon for hinges within polyclinal or composite folds. An unambiguous symbology is proposed, illustrated using hypothetical examples, and applied to the analysis of kilometre-scale folds mapped in the Rocky Mountain Foothills of northeastern British Columbia and the Franklin Mountain Liard Ranges of southeastern Yukon Territory and southwestern Northwest Territories.

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