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.
The geomorphic legacy of outburst floods: does boulder deposition from megaflooding control erosional patterns in the eastern Himalaya?
Abstract: The eastern Himalaya holds evidence for hundreds of temporary glacial and landslide dam impoundments throughout the Quaternary. Holocene glacial moraine dams at the Namche Barwa massif are thought to have impounded large lakes, producing megafloods (discharge >106 m3/s) after dam failure. These large, infrequent floods have been proposed as mechanisms of intense erosion during deglaciation in the Quaternary on the Yarlung-Siang River, however, their depositional footprint remains unexplored. Deposition from these floods in the form of boulders may feed back into erosional processes, controlling how and where sediment can move in the river during annual flows This project will assess the depositional impact of Quaternary megafloods within the Siang main channel from a paleohydraulic perspective. We will pair field measurements of boulder bars and channel widths with depth-averaged 2D numerical simulations of megafloods over 3D topography to explore the stability of these features in the channel and the implications for long-term river incision. We target boulder bars because recent numerical modelling of a historic landslide dam-break outburst flood down the Yarlung-Siang River suggests that large boulders can be deposited during outburst floods in unexpected areas. Boulders can exert a first-order control on sediment transport in coarse-grained systems by armoring the bed, increasing surface roughness, and extracting momentum from the flow. Boulders deposited during an outburst flood potentially control erosional and depositional patterns within the river if they are too large to be moved during average annual and peak flows. There are many large boulder bars in unexpected areas along the Siang River (i.e. at cut banks on meander bends where erosion is expected) suggesting they are not a product of average annual or peak flows. We will travel to the Siang River in Arunachal Pradesh, India in November 2019 to make field measurements of grain size and lithology of several out of place boulder bars in the Siang River. We will then use numerical modelling to simulate 2D hydraulic characteristics of two Quaternary megafloods to explore sediment transport dynamics at these boulder bars, validating these models with our field observations. Combined, field observations and numerical simulations will allow us to see what percent of these boulder bars can be moved during megafloods. Our results will begin to explore the lasting impact these large infrequent floods have on the Siang River and the surrounding hillslopes.
Quaternary deformation of the Hog Ranch-Naneum anticline, Yakima folds, Washington
Abstract: The Hog Ranch-Naneum anticline (HRNA) trends north-south through central Washington, USA, deforming the northwest-southeast trending Yakima folds and separates Kittitas Valley and the Columbia River. In this work, we ask: does an active fault account for the topographic expression of the HRNA? The Yakima folds are linked to post-Miocene tectonic uplift within the Cascadia backarc. Regional geologic mapping and aeromagnetic data suggests that initial tectonic uplift along the HRNA predates the Yakima folds. The HRNA also deforms the Columbia River Basalt Group (CRBG). Since the landscape within the fold province and HRNA was reset to relatively level relief ~15.6 Ma following the Grand Ronde Basalt member of the CRBG, deformation seems to have continued into Miocene time. However, the relative rate and precise timing of deformation of the HRNA is unknown. We use geomorphic and geophysical mapping, and stream profile inversion to examine activity and deformation history of the eastern boundary of the Kittitas Valley and the HRNA. We identified knickpoints in stream channels flowing from the crest of the HRNA into Kittitas valley. We anticipate to link active fault scarps on the western flank of the HRNA, and on the eastern side of Kittitas Valley to identified knickpoints. We also anticipate to date alluvial fan surfaces or strath terraces that are offset or incised by these active faults. The ages of offset surfaces will provide rates of deformation on the flanks of the HRNA or on faults bordering Kittitas Valley. Similar to recent studies in the region we anticipate that tephrachronology, cosmogenic 26Al-10Be isochron burial and/or luminescence dating techniques may inform ages of these Quaternary surfaces.
Investigating fault scarp degradation in jointed basalt in southern Iceland
Abstract: Fault scarps in jointed bedrock hold information key to illuminating a region’s recent tectonic history, such as timing of faulting and magnitude of events, if their morphological evolution through time can be deciphered. This project will investigate how jointed bedrock fault scarps record fault activity and determine the principal drivers of bedrock scarp degradation. This study will focus on characterizing this evolution in basalt-hosted normal fault scarps in southern Iceland, where scarps are abundant and well-exposed. The ongoing oceanic rifting in southern Iceland is marked by late Quaternary-to-recent tectono-volcanic systems identified as the East and West Volcanic Zones (EVZ and WVZ) and is characterized by numerous zones of fissures and faults that affect recent basaltic lava flows. In multiple sites, a single fault cuts through flows of various ages. Close correlation exists between the vertical throw of the major faults and the age of the affected lavas in outcrops, with scarps in Pleistocene flows exhibiting throws of several tens of meters or more and those in Holocene flows less than ten meters. Assuming continuous faulting in this region through the Holocene, we can use the age of the basalt flow as an approximation of the time of scarp formation. The morphology of a scarp from the same fault in each differently aged flow will thus offer a snapshot of its evolution through time, providing the opportunity to establish a space-for-time substitution investigating the tempo and style of scarp growth and degradation along a fault. This study will focus on characterizing the morphology of these bedrock scarps of different ages. We will quantify the degree to which these scarps have retreated through time by measuring the setback between the trace of the scarp in the youngest lava flows and those that preceded it. We will also determine the principal mechanisms of retreat and their timing. The processes that control the retreat of bedrock scarps have been explored in the specific contexts of waterfalls and glacial headwalls, but are still poorly constrained for fault scarps. We hypothesize that scarp degradation is dominated by strong ground motion, with scarps in the more seismically active areas experiencing higher rates of retreat. Cosmogenic exposure dating on a selected scarp will provide the overall retreat rate of the scarp and shed light on the processes that govern its degradation.