Dendrogeomorphological Analysis of Mass Movement on Table Cliffs Plateau, Utah

Abstract

A rock glacier-year, with little evidence of long-term surges. Different parts of the slope like boulder deposit on the Table Cliffs Plateau, Utah, has moved slowly over a long period of time and has affected over 220 trees growing on it. Analyses of annual rings of trees affected by this and other slope movements show events such as inclination, shear, corrasion, burial, exposure, inundation, and nudation. Datable responses to these events are reaction-wood growth, growth suppression and release, ring termination and new callous growth, sprouting, succession, and miscellaneous structural and morphological changes. Various events may produce delayed, antagonistic, interfering, or irrelevant event responses, necessitating procedural caution. A modified skeleton plot of yearly event responses was constructed for each sample in this study with only strongly replicating dates from within trees considered valid. The resulting event-response curve shows peak periods of movement centered around the years 1781, 1803, 1827, 1849, 1869, 1885, 1890, 1907, 1910, 1923, 1938, 1942, 1944, and 1958. Spectral analysis of the event-response curve, mean annual precipitation, and an independently derived tree-ring precipitation surrogate suggests a possible relation between precipitation and slope movement. Analyses of temperature data did not produce results in spite of the presence of internal ice which might be expected to contribute to movement. Map plots of movement through time show event responses scattered in linear zones throughout the slope during main episodes of movement in any given move at different times and some parts move more than others.