It was chosen for a comprehensive study of landslide processes because part of it apparently has been moving continuously for the past 300 years, transporting material hundreds of meters and repeatedly creating and destroying surface features such as folds and faults. Also, movement data have been collected periodically on the flow for more than 30 years. Lake San Cristobal is at lower right. The inactive landslide extends from the lake uphill to the active toe. Active toe is prominent light-colored bulge uphill from where Colorado State Highway 149 crosses the earth flow.
Active flow extends from active toe to prominent main scarp at top of photograph.
The Slumgullion earth flow occurs in altered Tertiary volcanic rocks and consists of a younger, active, upper part that moves on and over an older, much larger, inactive part. Based on radiocarbon and tree-ring dating, the younger, active part is about 300 years old. This Bulletin summarizes the presentations given at this meeting. The first six chapters are concerned with the geological aspects of our investigations. Chapter 1 summarizes the chronology of the Slumgullion slide and presents some additional background on local surficial geology.