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. Since the program’s launch in 2014, we have funded over 100 research projects.
Abstract: Astoria Canyon was the submarine extension of the Columbia River discharge during low-stand conditions in the late Pleistocene and early Holocene. However, under current high-stand conditions, the connection between Astoria Canyon and the Columbia River is less direct, with the mouth of the Columbia separated from the canyon head by about 20 km. Although the Columbia River remains the likely source of any modern sediment-gravity flows down Astoria canyon, the processes of transport, deposition, and remobilization on the continental shelf have imparted signatures on any Columbia River sediment reaching Astoria Canyon. The goal of this work is to characterize deposits of Columbia-derived sediment along a transect between the modern river mouth and the head of Astoria Canyon. The depositional history (via 210Pb geochronology) and sediment characteristics (e.g., grain size, physical structure, porosity) of shelf sediments will be compared with active sedimentation processes in the head of Astoria. By comparing the century-scale history of deposits on the shelf with modern sedimentation in the canyon head, we will improve our understanding about the the degree of coupling between modern sediment discharge from the Columbia River and delivery to Astoria Canyon.
Sediment Supply to Astoria Canyon: Canyon Head Sedimentary Processes
Abstract: During low stands in sea level, Astoria Canyon was the submarine extension of the Columbia River dispersal system and many of the submarine deposits associated with it (e.g., Astoria Fan) are thought to have been sourced from the Columbia River. However, in modern conditions, sources of sediment to Astoria Canyon are less well understood, and could include erosion of local canyon walls, wave-supported sediment gravity flows, or bottom-boundary layer advection of sediments. Hydro- and sediment dynamics of the Astoria Canyon head will be examined using an instrumented benthic tripod as part of a USGS-funded project.
With this additional work supported by QRC we will expand the scope of that project to examine modern sedimentation within the canyon head using a combination of surface grab and box core sampling, and deployment of sediment traps in conjunction with the instrumented tripod. The proposed instrument deployment will encompass a summer field season, and thus we can evaluate dynamics and conditions by adding ship-based sampling when the tripod is deployed and retrieved (proposed for June and September of 2019, dependent on collaborative UW-USGS ship-time scheduling). The canyon head has complex morphology, and thus differing dynamics and sediment-accumulation patterns, and capturing a range of variability is essential not only for evaluating the erodibility and geotechnical strength of the sediment, but also for targeting future coring efforts. The characteristics of these modern sediments (e.g., grain size) will be compared with sediment cores collected on the shelf (see linked QRC project, PI Fricke). This will help determine whether sediment actively transported or deposited in the head of Astoria Canyon is derived from local sources, or shelf sediments, and if the latter, the degree of reworking (i.e., winnowing) of those source deposits. Dynamical measurements collected with the USGS-funded instrumented tripod will constrain the type and intensity of processes responsible for the remobilization and modification of material reaching the canyon head.