Fabric analysis of rock glacier debris mantles, La Sal Mountains, Utah

Macrofabrics of rock glacier debris mantles display significant variation even among similar microtopographic features. Fabrics of longitudinal ridges of La Sal rock glaciers are equally divided between cluster and girdle distributions. In some cases, fabric patterns resemble those of lahars, implying that the flow mechanics of rock glaciers bears some similarity to that of large‐scale debris flows. Shear zones are found at the margins of many longitudinal ridges, and in at least one case these zones separate the rock glacier from a pair of bounding ridges that resemble debris‐flow levees. Other sites display fabric patterns that indicate that the dominant processes are dry creep of the open‐matrix debris mantle. Weak fabrics are found at sites where rockfall inputs occur on a low‐angle surface, or where a debris mantle is undergoing passive transport by a moving core.