Sediment movement and storage on alpine slopes in the Colorado Rocky Mountains

Contemporary rates of sediment movement on alpine slopes in three basins in the Colorado Rocky Mountains have been estimated for periods which range up to 20 years. In that time, hillslope processes on a basin-wide scale are dominated by mass transfers within the cliff-talus system, especially by work done in infrequent rockfalls involving more than 5 m³ of debris. Almost all transfers of clastic sediment remain internal to the slopes which are therefore effectively decoupled from the stream channels below them. The only significant exception to this involves silt and clay, imported to the alpine system through the atmosphere, which is transported via the streams to alpine lakes. The closure of the slope systems appears to have been effective for most of the Holocene. Even on that time scale, slope processes have had little influence on landform generation.