Asymmetric valleys are those in which opposing sides have markedly different inclinations (Fig. 1). A method of indicating this disparity is the symmetry index (Emery, 1947) which is the ratio of the average inclination (in degrees) of the left side of the valley to the inclination of the right side of the valley, where left and right sides are relative to an observer facing downstream. If a valley is perfectly symmetrical, the index will be 1.0; if the left wall is steeper, the index will be greater than 1.0; if the right wall is steeper, the index will be less than 1.0. This index has not been widely used, perhaps because it involves large integers as well as small fractions. An alternative would be to subtract the average inclination of the right valley side from the average inclination of the left valley side. If the left side is steeper, the valley will have a “positive asymmetry”; if the right side is steeper, the valley will have a “negative asymmetry”; if the valley sides have...
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Cross-references
Abrasion; Baer—Babinet Law; Cirques; Cryology, Cryosphere, Cryergy; Denudation; Drainage Patterns; Duricrust; Frost Action; Geomorphology; Mass Wasting; Nivation; Periglacial Landscapes; Quaternary Period; Rivers; Sheet Erosion, Sheetwash, Rainwash, Sheetflood; Slip-off Slope; Slope Analysis; Slopes; Solifluction; Valley Evolution; Weathering.
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Wilson, L. (1968). Asymmetric valleys. In: Geomorphology. Encyclopedia of Earth Science. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-31060-6_16
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DOI: https://doi.org/10.1007/3-540-31060-6_16
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