QRC members lead and participate in a wide range of disciplinary and interdisciplinary research projects from the study of past earth climates and glaciations to shifts in the geographic distributions and evolution of vegetation and faunal communities, to the evolution and dispersals of the genus Homo and the increasing scales of human modification of earth environments through the Holocene. QRC provides a venue for meeting and collaborating with scholars across Quaternary disciplines. We are also fortunate to be able to provide seed funding and small grants for member research projects. We are especially happy to support grad student and junior scholar research activities, much of which leads to larger, external funding from agencies like the National Science Foundation.
River incision driven by changes to woody debris and sediment retention
Abstract: The proposed project uses field observations, dating, and numerical dating to investigate the short- and long-term effect of sediment retention on river incision and landscape evolution. River incision is thought to be controlled by the balance of sediment supply and transport capacity, with the largest changes in incision rates occurring at glacial-interglacial transitions (e.g., Hancock and Anderson, 2002; Turowski et al., 2007; 2008; Yanites and Tucker, 2010). However, the current framework only considers the transport of sediment and does not take into account any impediments to transport – such as large woody debris (LWD) jams and rockfall – that retain sediment on the riverbed. During enhanced sediment retention, bedrock is protected from erosion by a thick sediment cover (Sklar and Dietrich, 2001); reduced retention will have the opposite impact and promote incision. Such an effect has been noted in streams containing LWD wherein bedrock streams are converted to alluvial by the added retention (Montgomery et al., 1996; Massong and Montgomery, 2000; Faustini and Jones, 2003). Although the conversion of bed-cover has been noted, it is unclear how sediment retention will affect river incision rates. Can a sudden decrease in sediment retention result in significant incision? If so, is the effect of varying retention strong enough to leave a morphologic signature over the Quaternary? We are particularly interested in sediment retention’s impact on strath terrace formation. Strath, or bedrock, terraces are often used to infer Quaternary rates of tectonic deformation (e.g. Personius, 1993; Merritts et al., 1994; Lave and Avouac, 2001); if sediment retention can affect incision rates, then we need to consider changes to sediment retention before making inferences regarding tectonic strain.