APPLICATION OF RELATIVE-AGE DATING TECHNIQUES ON ROCK GLACIERS OF THELA SAL MOUNTAINS, UTAH - AN INTERPRETATION OF HOLOCENE PALEOCLIMATES

This paper applies a variety of relative-age dating techniques on rock glaciers of the La Sal Mountains, Utah to interpret the area's Holoce ne paleoclimates. Relative ages of rock glaciers and talus of the La S al Mountains, Utah, were determined using several techniques: lichenom etry, Schmidt-hammer rebound value, clast roundness, clast surface rou ghness, and weathering rind thickness. The techniques were compared ag ainst one another and evaluated as to their effectiveness. Lichenometr y can be used to differentiate among depositional episodes of the past 2-3000 yrs, but lichens are sometimes adversely affected by environme ntal factors such as prolonged snowcover, which can periodically reduc e or eliminate thalli. Rock hardness, as measured by the Schmidt hamme r, and roundness did not prove to be particularly useful in differenti ating sites. Weathering rind development is less subject to variations in rate, and its measurement is less subjective than most of the othe r methods. Weathering rinds were therefore used in conjunction with Li chenometry to establish a Holocene paleoclimatic chronology. The combi nation of methods permits some potential disadvantages of lichenometry to be exploited to advantage and used for paleoenvironmental interpre tation. Data support a threefold sequence of deposition during the lat e Holocene. Weathering rind data indicate deposition in early Holocene -late Pleistocene as well, but precise relative-dating of this older m aterial is beyond the resolving abilities of these techniques. Our con clusions are in general agreement with radiometrically-based Holocene chronologies of the Colorado Front Range.