FABRIC ANALYSIS OF ROCK GLACIER DEBRIS MANTLES, LA-SAL MOUNTAINS, UTAH

Macrofabrics of rock glacier debris mantles display significant variat ion even among similar microtopographic features. Fabrics of longitudi nal ridges of La Sal rock glaciers are equally divided between cluster and girdle distributions. In some cases, fabric patterns resemble tho se of lahars, implying that the flow mechanics of rock glaciers bears some similarity to that of large-scale debris flows. Shear zones are f ound at the margins of many longitudinal ridges, and in at least one c ase these zones separate the rock glacier from a pair of bounding ridg es that resemble debris-flow levees. Other sites display fabric patter ns 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 under going passive transport by a moving core.