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.
Assessing Rock Surface Erosion Using Cosmogenic Isotopes and Optically Simulated Luminescence Depth Profiling in Petroglyph Contexts
Abstract: Petroglyphs, rock images created by the anthropogenic removal of material on a rock surface, are subjected to various natural and anthropogenic conditions that cause them to degrade over time and eventually disappear. Accurate quantification of the erosive impacts on petroglyph surfaces and identifying and understanding the environmental factors of erosion can be essential for planning preservation strategies.
A multidisciplinary scientific analysis utilizing geochemical and paleoenvironmental analysis methods at petroglyph bearing sites will be conducted at Henry W. Coe State Park, located in the Diablo Range of Northern California, to assess the history of and factors contributing to rock surface erosion. This analysis will primarily focus on utilizing concentrations of cosmogenic isotope 10Be from rock surface samples in proximity to petroglyphs to establish proximal rock erosion rates to petroglyph surfaces. Using the data, erosion episodicity (whether spallated, gradual, etc.) may also be determined via applied modeling. Cosmogenic erosion data will be co-analyzed with optically simulated luminescence (OSL) depth profiling analyses on similar/same rock surfaces to decipher any unique environmental settings that may impact each method’s results. Providing a cosmogenic-OSL dual analysis also helps introduce cosmogenic isotopes to archaeological study in a way that easily relates cosmogenic isotopic methods to OSL, making it easier to understand and incorporate cosmogenic isotopes in future archaeological work. The same can be said for Earth scientists interested in rock erosion analyses yet are less familiar with OSL, which is an underutilized tool in the Earth Sciences yet hosts great potential for surface process study. No samples directly from petroglyph surfaces will be taken. Additional paleoenvironmental analyses of the petroglyph region will also be carried out, utilizing a multitude of methods such as palynology, rock-vegetation interaction analyses, Landscape Reconstruction Algorithms (LRA), and other relevant paleoenvironmental methods that will be uniquely applicable to the site. Once gathered, a comparative analysis utilizing the quantitative erosion data and paleoenvironmental records will then be conducted to provide a better understanding of the erosive history of petroglyph surfaces and help identify the environmental factors affecting erosion rates. This knowledge may offer needed data for communities and parks wanting to optimize the preservation of their material heritage.
Addressing Rock Artifact Erosion in Mount Diablo State Park, California
Abstract: Abstract (500 words MAX for website purposes)
Artifact bearing sandstone surfaces located in Mount Diablo State Park, California face vandalization and surface degradation from graffiti, foot traffic, grazing, and other anthropogenic influences in addition to broader, longer term effects from Holocene scale microclimatic and environmental changes in the region. Artifacts in the park are currently protected under vandalization clauses, yet a surface stability study may assist in the development of and support toward more effective protection efforts by providing a clearer understanding of the erosive mechanisms altering artifact surfaces. Thus, it is desired from the Mount Diablo community to conduct a quantified, millennial scale study of artifact surface stability. This project attempts to address this desire by selecting four non-artifact sandstone surfaces from two artifact bearing campground sites in the park and analyzing their surface stability histories using a combination of multidisciplinary procedures. Optically stimulated luminescence (OSL) depth profiling will be conducted on extracted rock cores from the sandstone surfaces to produce calculated steady-state centennial to millennial scale surface erosion rates and provide relative surface stability histories of the same scale using luminescence depth curves that document variations in surface luminescence though time. Steady-state erosion rates from sandstone surfaces will also be calculated with 10Be surface data using CRONUS, and then compared with OSL results to identify potential differences with each measurement’s interactions to surface variables (lichens, moss, mineralogy, etc.). Millennial scale probabilistic rock surface spalling analyses also using 10Be data will be incorporated in the analysis to determine possible sequences of surface re-zeroing events that may influence CRONUS and OSL data. Indications of artifact surface erosion influenced by local climatic changes and/or anthropogenic landscape alterations will be analyzed by connecting trends in luminescence attenuation, cosmogenic spalling, and erosion data to distinct historical and prehistorical variations in regional vegetation cover. To make these comparisons, pollen-derived landscape reconstruction algorithms (LRAs) that document regional Holocene vegetative cover through time will be conducted in the Mount Diablo region using pollen sampled from five regionally spaced soil cores within the region. Additional comparisons to historical data and geomorphic observations will also be made to observe direct anthropogenic influences on artifact surface erosion and the landscape. Through comparing millennial scale artifact surface erosion stability data to environmental, climatic and anthropogenic histories in the Mount Diablo region, primary agents and sequences of artifact erosion can be identified from our procedures, providing analytical support for park agendas that aim to mitigate identified erosive factors. The success of this analysis in Mount Diablo can justify the method’s use at other rock artifact bearing sites.
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.
Reconstructing seed dispersal paleoecology in the North American Great Plains
Abstract: The earliest evidence for grass dominated habitats in the Great Plains region appears in the fossil record around 25 million years ago. Since then, the region has experienced significant climatic, floral, and faunal changes. My research investigates how changes in the structure of North American grasslands affected the ecology of grasses in the region, with a particular focus on seed dispersal.
Modern grasses display a variety of dispersal strategies, exploiting both biotic and abiotic vectors to spread their seeds, and we have hypothesized that the initial expansion of grass dominated habitats in the Great Plains region precipitated changes in the dispersal ecology of its major grass constituents. I am testing this hypothesis using both living grasses and fossilized grass seeds. The morphology of the grass diaspore (seed dispersal structure) reflects how it is dispersed, and by studying the morphology of the diaspores of modern and fossil grasses, we can understand the dispersal ecology of grasses in North America’s earliest grasslands, how it has changed through time, and how it compares with today.
One aspect of this research focuses particularly on understanding how reliably our fossils preserve the dispersal structures of the grasses in those early grasslands. Fossil diaspores are preserved as 3D silicifications, and their preservation is believed to be dependent upon those structures being indurate, and well silicified in life. Many grasses possess bristle-like appendages called awns, which often play a critical role in seed dispersal. The fossils we use are found lacking awns, but it is unclear whether this reflects a preservation bias or whether the awns were shed prior to dispersal (as occurs in some of these grasses modern relatives). To address this question we are assessing the preservation potential of the different parts of the diaspore in a variety of modern grasses, by evaluating the relative silicon concentrations of each. To do this, we are growing a large number of grasses in the new Life Science Building greenhouse and using X-ray fluorescence spectrometry to quantify the level of silicon deposition in the awn relative to the main body of the diaspore.
Once the morphology of fossil diaspores is better understood, we can try to reconstruct how seeds were dispersed. To do this, we are constructing an eco-morphospace based upon measurable traits associated with particular methods of seed dispersal. By incorporating grasses into this space, their seed dispersal strategies can be compared in a quantitative manner. Importantly, the chosen metrics can all be directly measured or reasonably estimated from fossil grass diaspores. By incorporating fossils into this morphospace we will track how dispersal ecology changed through time, and how the grass communities of the past compare to those found in modern grasslands.
Constraining ages of glacial deposits recorded in a Victoria Valley permafrost core
Abstract: The past stability of the East Antarctic Ice Sheet (EAIS) remains an important, yet unsettled question. Efforts to address this question focus on EAIS stability during the Pliocene (5.33-2.58 Mya), a period characterized by CO2 levels comparable to today’s levels and global mean temperature comparable to those predicted for the end of the century. While the marine record from the Antarctic Drilling Project (ANDRILL) and recent ice-sheet models suggest a dynamic EAIS during the Pliocene, there is not yet strong corresponding terrestrial evidence of a dynamic Pliocene EAIS. Stratigraphic and geomorphic evidence of glacial deposits from EAIS outlet glaciers in the Antarctic Dry Valleys may provide the much-needed terrestrial record of EAIS stability. Here, a 15-meter ice-cemented permafrost core collected in Victoria Valley is analyzed using cosmogenic nuclides to provide quantitative constraints on the timing of the EAIS glacial history in the Dry Valleys. Based on the presence of oxidized layers from apparent paleosols, the core appears to have recorded four depositional events that are believed to represent different periods of glaciation. Each depositional unit was deposited and exposed to cosmic rays at the surface until subsequently buried during the next glacial event that then shielded the sediment from further cosmic ray exposure. Sediment was subsampled in the core at the upper, middle, and lower limits of each depositional unit and analyzed for 10Be and 26Al, as well as texture, soluble salts, and other parameters. Several possible models of the burial history, accounting for exposure time, burial time, and inherited nuclides, are tested using inverse modeling techniques to provide a timeline for EAIS history in Victoria Valley. Preliminary results of the four units show ages of 30 Ka, 1.05 Ma, 2.4 Ma, and 3.9 Ma, suggesting the earliest expansion of the EAIS coincides with the warmer and wetter conditions during the Pliocene and corroborates the ANDRILL findings.
Evidence for liquefaction and flooding in the past 1,000 years along the Duwamish River, Seattle, Washington
Abstract: Geology along the Duwamish waterway, just south of downtown Seattle, provides preliminary clues to the city’s earthquake hazard. The banks of the dredged waterway expose the muddy deposits of an estuary that formerly drained Mount Rainier. Evidence for multiple episodes of liquefaction and unusual floods within the past 1,000 years have been pieced together from a few outcrops which record different aspects of the site’s history.
So far, inferred events include two episodes of liquefaction and two unusual floods from land or sea. All events post-date the large Seattle fault earthquake of 900—930 CE. Evidence for liquefaction consists of dikes and extrusive lenses of andesitic sand among muddy tidal deposits. The sand was likely vented from lahar runout deposits that underlie the tidal mud. Two persistent, horizontal silt layers observed in one outcrop suggest unusual flooding, either from Puget Sound or from upriver. Age control on the deposits comes in the form of radiocarbon ages of marsh plant fossils.
Additional dikes have been observed but have yet to be well-dated. Findings from this project may yield insights into Seattle’s earthquake and tsunami hazards.
Decadal-scale impacts of mangrove removal: Re-evaluation of sediment characteristics and transport >10-years after mangrove removal in Tauranga Harbor, New Zealand
Abstract: Mangrove forests occupy the complex intersection of geomorphology, oceanography, forestry, and anthropology. As the only large woody plant that grows in the intertidal zone, mangroves directly impact coastal stability and morphology by rapidly colonizing prograding shorelines, retaining sediment, and damping wave energy. Unfortunately, mangrove forests are threatened by accelerating deforestation, and there is very little data on decade- to century-scale change following mangrove removal. A mangrove clearing project in Tauranga Harbor, New Zealand has provided a rare opportunity to observe decadal-scale, geomorphic changes associated with deforestation. Patchy mangrove removal in 2005 created a natural laboratory to compare sedimentary processes on naturally unvegetated, forested, and cleared intertidal surfaces of the harbor. Changes to the estuarine morphology and sediment transport were evaluated during and immediately after the clearing in the Waikaraka Estuary of Tauranga Harbor. This estuary will now be reexamined in June 2019 through a collaboration between UW, Southern Cross University, and the University of Waikato. We will examine the physiognomy of the mangrove stands, evaluate sediment transport using acoustic current meters and sediment traps, and collect cores of the upper 1-m of sediment. The cores will be analyzed for grain size and organic content. Accumulation rates will be calculated using 210Pb. These measurements will be used to assess the physical changes which have occurred and predict the future evolution of this estuary. We are grateful for the support of the QRC, which will enable us to use deploy the acoustic instruments and conduct the 210Pb analysis. These measurements add quantitative evaluation of the previously published patterns of sediment transport and geomorphic change. This field study will improve our understanding of past and future coastal change associated with deforestation.
A search for pre-LGM megaflood sedimentation in Cascadia Basin
Abstract: Marine sediments along the Cascadia margin are likely to contain continuous, long-term records of marine and continental change in the Pacific Northwest over the last several million years. While glaciations, floods, and erosion have reworked the terrestrial record, many marine sites had continuous deposition over this timespan. Such sites are potential archives of oceanographic history, meltwater influx, density-current processes, subduction zone tectonics, and landscape evolution. We propose to study two legacy sediment cores from Cascadia Basin, focusing on depositional chronology and tracers of sediment provenance. The two cores, Deep Sea Drilling Program (DSDP) Sites 174 and 175 are by far the deepest cores from this region, and thus unique in their recovery of sediment spanning multiple glacial-interglacial cycles. This work is a first step towards finding and developing long-term records of megafloods down the Columbia River and understanding Cascadia Basin sedimentation throughout the Pleistocene.
Freezing soils and patterned ground in the tropics
Abstract: Geophysical patterns form spontaneously in diverse settings and environments, in response to non-linear processes. Notable examples include sand dunes and ripples, beach cusps, stalactites, icicles, columnar joints, and patterned ground. These patterns not only attract the eye, but they also stimulate studies that often yield fundamental insights of broad interest . Decades ago, we launched a study of a spectacular example of patterned ground, sorted stripes, near the summit of Mauna Kea (Hawaii) that is absolutely striking because of its geometry regularity (see accompanying photograph). This study is deeply rooted in QRC; Steve Porter catalyzed it, and it addresses periglacial patterned ground, the principal research interest of QRC’s founder, Lincoln Washburn .
This project will complete the work to date, solidify previous results and complement them with new data that will help 1) bring to fruition perhaps the most comprehensive study of periglacial hillslope activity and self-organization to date, and 2) improve understanding of patterned ground and the motion of surface soil and pebbles on alpine hillslopes.
Earth Rover – A low budget, expandable, autonomous platform for exploring the Pacific Northwest
Abstract: This product, designed to support data collection in unsampled regions of glaciers where high strain rates crevasse the ice surface, and oversteepened tributary walls induce avalanching will expand the sampling capabilities of UW earth scientists in the pacific Northwest. Working with students from UW mechanical engineering, we will build on an established rover design by developing steering vision, and suspension systems that will optimize the rover’s turning efficiency and mobility over uneven mountainous terrain. The final rover product will be deployed on Easton Glacier, measuring surface elevation change via photogrammetry, snow depth and snow water equivalent from ground-penetrating radar, and glacier velocities from stationary rover GPS measurements. The high impact science and research potential of our modular design will enhance collaborations with the UW engineering and the Quaternary Research Center, and our modular configuration extends Earth Rover’s applications beyond the cryosphere. We anticipate applications in other areas of the geosciences, archeology, and civil and environmental engineering. The co-educational development of our terrestrial Rover will bring these disciplines together on a collaborative project that will continue with further rover development and project integration.
Was the Lost Lake landslide on Vashon Island triggered by an Earthquake?
Abstract: Landslides are a common and potentially deadly hazard in the Puget Lowland. The Puget Lowland experiences both deep seated and shallow landslides which are commonly driven by precipitation but can also be triggered coseismically. To distinguish between failure types and to constrain failure age, landslides are often mapped using their geomorphic features and dated using radiocarbon or dendrochronology. Such landslide maps and chronologies are a first and necessary step in trigger and risk assessment. Previous studies have mapped and dated multiple submerged coseismically triggered landside deposits within Lake Washington. The submarine deposits and submerged forests are associated with the 900 A.D. Seattle Fault Earthquake. Despite the significance of their findings there is a lack of evidence for coseismic landslides in the Puget Sound. However, one potentially co-seismic landslide is the Lost Lake Landslide, located on the southern tip of Vashon Island and situated between both the Seattle Fault and Tacoma Fault Zones. Beyond being younger than the last glaciation of the Puget Lowland, no age constraint exists for the landslide, thus lacking the age resolution needed to distinguish it as coseismically triggered. Additionally, the lack of detailed geomorphic mapping of the Lost Lake landslide limits the potential for comparing its geomorphic features with other Puget Lowland landslides of unknown age. We will create a detailed geomorphic map of the Lost Lake landslide and determine the age of the landside using radiocarbon dating and dendrochronology. Our goals are to determine if the age of the landslide matches with any sizable earthquakes in the region and to provide more data for comparing geomorphic features, such as roughness, with landslide age. We anticipate that, regardless of the age of the Lost Lake landslide, our new mapping and characterization of the slide will be valuable to future landslide hazard maps in the Puget Lowland. If however, the age is determined as coseismic, it will help refine our understanding of how the Puget Lowland landscape will respond to a future large magnitude earthquake. Our results could also contribute to Puget Lowland roughness model calibration and help identify other coseismic landslides based on geomorphic features identified during field and lidar mapping. We believe that the Lost Lake landslide presents a unique opportunity to map and date a large and potentially coseismic landslide. Through this process we hope to not only identify a coseismic landslide but to contribute to a general knowledge of landslide features associated with age.
Abstract: Glaciers in Central Asia present an excellent opportunity to test glacier sensitivity to various climate settings. During the global last glacial maximum, around 20,000 years ago, glaciers in southern Siberia and Altay mountains hosted large glacier-dams to originate some of the largest outburst floods on Earth. Central Mongolia shows a similar pattern of glacier advances, in addition to slightly bigger glaciers ~30,000 years ago. In contrast, Bataa discovered that hyper-arid Gobi glaciated during the warmest period of the early-middle Holocene, with no evidence of glaciations during the coldest of the last ice age. In that condition sunlight provides sufficient energy to evaporate the ice from these precipitation-starved glaciers. This phenomenon was first observed in dry parts of the Kyrgyz Tien Shan, and now similar ‘peculiarity’ in the high roofs of Tibet have been discovered. This project aimed to constrain the chronology of glaciers in key locations, and compile a map of paleo-glaciers with different sensitivities.
Dating newly suspected MIS2 moraines in Central Asia by CRN
Abstract: Glaciers in Central Asia present an excellent opportunity to test glacier sensitivity to various climate settings. During the global last glacial maximum, around 20,000 years ago, glaciers in southern Siberia and Altay mountains hosted large glacier-dams to originate some of the largest outburst floods on Earth. Central Mongolia shows a similar pattern of glacier advances, in addition to slightly bigger glaciers ~30,000 years ago. In contrast, we have discovered that hyper-arid Gobi glaciated during the warmest period of the early-middle Holocene, with no evidence of glaciations during the coldest of the last ice age. In that condition sunlight provides sufficient energy to evaporate the ice from these precipitation-starved glaciers. This phenomenon was first observed in dry parts of the Kyrgyz Tien Shan, and now we’ve also discovered similar ‘peculiarity’ in the high roofs of Tibet. This project aims to constrain the chronology of glaciers in key locations, and compile a map of paleo-glaciers with different sensitivities.
The Emergence of Iron Metallurgy in Taiwan: a Trade Diaspora Model
Abstract: My research takes a new approach to investigating the emergence of prehistoric iron metallurgy in Taiwan by using a trade diaspora model, which privileges the role of trade diasporic “foreigner” communities and their interactions with local communities. Trade diaspora are characterized by groups of merchants who travel far from home and locate themselves in a different community to trade goods and provide services. Recently, archaeologists have applied the concept of trade diaspora to explain the interaction between foreign immigrants and indigenous people in historic periods. My project will use the trade diaspora model to explain archaeological data from a time period in Taiwan pre-dating the appearance of documentary historical records, about 1800 years ago.
LEIA Paleoenvironmental Pilot Project
Abstract: The LEIA PALEOENVIRONMENTAL PILOT PROJECT aims at providing preliminary baseline paleoenvironmental information to the on-going UW LANDSCAPE, ENCOUNTERS AND IDENTITY ARCHAEOLOGY PROJECT (LEIAP, HTTP://LEIAP.WEEBLY.COM/). The latter is a UW lead landscape archaeology fieldschool project that seeks to reconstruct the history of occupation and land use of the Son Servera landscape (E. Mallorca, Spain) spanning from Late Bronze Age (c. 1300 cal. BCE) to early modern times. It represents the first comprehensive landscape project ever carried out in Mallorca (and the Balearic Islands) that combines very intensive surface survey with targeted excavations aimed at collecting datable material to tie chronologically the construction, use and abandonment of known sites with landscape-wide processes. The LEIA PALEOENVIRONMENTAL PILOT PROJECT, focuses, more precisely on the collection and analysis of a series of paleo-vegetation (pollen) and anthropogenic fire cores, as well as, basic geomorphological mapping for the study area.
A major asset of the LEIA project is the collection of large amounts of geo-located +27,000 dGPS surface collection points, roughly 10m apart (±2m SE), from which almost 28,000 artifacts (all classified by period, weighed and measured) have been retrieved. Thus, the LEIA project is ideally primed to combine this rich archaeological dataset with paleoenvironmental information to begin exploring how recurrent local practices, trade contacts and invasions may have shaped the local landscape.
The LEIA PALEOENVIRONMENTAL PILOT PROJECT seeks to start redressing the current deficiency in paleoenvironmental information through a series of smaller projects aimed at answering specific questions:
- The collection of preliminary palynological information aimed at reconstructing vegetation history of our study area (Is there evidence of a vegetation shift during the mid to late fourth millennium? Did increase contact with the greater Mediterranean during the late first millennium brings upon changes in landscape exploitation?)
- The processing of geomorphological samples aimed at identifying and characterizing major erosion and sedimentary episodes in the Serverin landscape. (how reliable are our reconstructions of landscape occupation based on our survey results? what periods show clear evidence of human induced erosion?)
- The processing of field samples aimed at assessing the possible use, and impact, of anthropogenic fire through time. (how early did the use of fire for landscape management started in Mallorca? What areas in the landscape were targeted)?
This is a collaborative project with other Spanish (Biel Servera, Jordi Hernandez-Gasch, Anton Puig) and US (Grant Snitker, Nari Miller) researchers.
Integrating Steller Sea Lion Archaeogenomics with Archaeological Data to Understand Human-Marine Ecosystem Interactions and Demographic Shifts in the Kuril Islands
Abstract: This project uses ancient DNA analysis of Steller sea lion remains from the Kuril Islands to investigate a human population collapse that occurred around 1000 B.P., associated with the Okhotsk culture. I will also provide paleoecological data that can be used to better understand contemporary pinniped populations and the threats facing them. Sea lions are being used to investigate human population collapse because they were relied on both for subsistence and resources by the people of the Kuril Islands. If the decline in the Okhotsk population is related to a decrease in the abundance of marine resources, a correlating bottleneck in sea lion populations may be evident in the archaeogenomic record. A sea lion population bottleneck would not be the direct cause of a human population decrease, but it would signal human pressure on the marine environment and/or an external climatic event affecting people and their resources. If there is no change in population structure of sea lions during the Okhotsk collapse, environmental stresses may not have been a factor in their decline. I will use the genetic data obtained from the sea lions to test for ancient population structure in sea lions, test for demographic decline, and look for signs of “genomic meltdown.” This research serves as pilot work for my dissertation in which I will use these methods as a means for understanding larger scale human-marine environment interactions in the North Pacific Rim region throughout the Holocene.
Ancient plant community and climate of the Pacific Northwest (USA) during the Middle Miocene Climatic Optimum: The Emerald Creek Flora of Northern Idaho
Abstract: This study will combine plant microfossils (i.e., pollen/spores and phytoliths) and macrofossils (e.g., leaves) from the Emerald Creek flora of Idaho to reconstruct vegetation and climate during the Middle Miocene Climatic Optimum (MMCO). The MMCO occurred ~17–14 million years ago and is one of Earth’s most recent transient warming events. Previous studies of vegetational and climatic response to the MMCO in the western U.S. have utilized different paleobotanical sources (macrofossils or phytoliths) that arrive at conflicting inferences. Understanding why these differences exist is problematic because of several potential confounding factors, including age differences, regional-specific factors (e.g., topography), and differences in what ecological information each source captures, particularly within patchy landscapes. I hypothesize that different paleobotanical sources reflect vegetation within distinct areas of the landscape and thus confound comparisons between studies using different sources when ancient vegetation was patchy. By integrating paleobotanical sources from a single fossil site and sediment horizon I will provide a spatially and temporally resolved perspective of vegetation and climate. Specifically, I predict that at Emerald Creek, macrofossils will disclose a diverse, mainly broadleaved riparian forest, while pollen and phytoliths will disclose an upland, open-habitat grassland—woodland mosaic, all existing in a warm-temperate sub-arid climate. This study will demonstrate the utility of using multiple paleobotanical sources in gaining a comprehensive view of ancient vegetation and climate and provide such a perspective for vegetation and climate in the Pacific Northwest during the MMCO.
Re-evaluating of the geology and archaeology of the Chauk region, Myanmar: New approached to an archaeologically significant landscape in Southeast Asia
Abstract: The Chauk region of central Myanmar is important as the source of oft-repeated but untested claims about Middle Pleistocene human occupation of mainland Southeast Asia. In the 1930s Hallam Movius and others made a cursory survey of the area, and reported surface finds of stone artefacts and a model of Plio-Pleistocene landscape evolution. Movius’ model proposed a series of river terraces formed during the Pleistocene and correlated to the last glacial-interglacial cycles. Stone artefacts found on the surface of these terraces were argued by Movius to have been placed there shortly after the terraces formed. This claim is based partly on his interpretation of the terrace chronology, and partly on assumptions about the antiquity of the artefacts due to their simple appearance. From this claim comes the concept of the ‘Movius Line’, which roughly divides the Palaeolithic world into a western hemisphere (where handaxes and and other bifaces are present) and the eastern hemisphere (where they are absent). Defining and explaining the Movius Line is an active debate in modern Palaeolithic Archaeology.
Despite the prominence of the Movius Line in discussions of global patterns of human evolution, there has not been any new data from the location of Line since Movius’ initial field work. The glacio-eustatic nature of the terraces is itself doubtful, which would prevent any correlation with their European analogs, as previously done by Movius and Terra. There is no absolute chronology – the terraces have not been investigated using radiometric methods. There has been no analysis of the stone artefacts to verify that they are human-made and rather than natural, a strong possibility given their proximity to a seasonally high-energy river.
This pilot project proposes to address these gaps in our knowledge of Southeast Asian archeology. We aim to (1) determine the nature of the terraces by careful geological mapping and study of sediment provenance; (2) collect samples for dating them; (3) survey for stone artefacts on the surface to collect for detailed analysis. New landscape maps and descriptions will directly add to our knowledge of landscape evolution in this region. New dates will allow us to make novel, robust comparisons to regional Quaternary dynamics. Archaeological finds will facilitate comparisons with nearby regions and periods from which we can infer technological connections or isolation.
Tibet Moraines Project
Abstract: From dating of lake sediments from a QRC trip to NE India, it is clear there were historical floods (e.g., 750 AD), and from the Chinese dating it is clear there were several earlier ones during the Pleistocene. In 2004, samples were collected that allowed dating the times during which there may have been major ice dams across the Yarlong Tsangpo, but most of these samples have not been analyzed as the chronology of glacial damming was outside of the scope of the project that supported the fieldwork. The QRC trip to NE India collected samples of flood deposits that have been dated to the time of the most recent Tibetan lake sediments. This project proposed to date the remaining samples from Tibet using cosmic ray exposure analysis with Be-10 for boulders sampled from moraines and OSL for sands from lake sediment exposures. These data will provide a much-enlarged chronology of ancient glacial river damming (and thus outburst flooding) events that will be of great use for an ongoing project (Huntington/Montgomery) dating the Tsangpo flood deposits in NE India. The goal is to combine our existing dates on Tibetan lake sediments and dated moraine dams collected by Gillespie, Montgomery, and Henck, with downstream flood deposits collected by Larson, Montgomery, and Huntington to write a group QRC paper that ties these observations together (through the dates) and sets the stage for further work in the region.
Low-Impact Recording Methods in Rock Art Studies
Abstract: This collections-based dissertation project includes a suite of complementary, non-destructive, or low-impact data collection methods such as archival research, collaborations with cultural advisors and elders, digital data collection, and regional spatial analyses to analyze Chinookan-Columbia River ground stone artifacts, or belongings. The focus of this investigation is to examine carved and painted portable rock art and connect them to important places on the Lower Columbia River landscape by identifying distinct artistic styles, motifs, geochemical signatures, and/or practices unique to historically documented communities. The spatial distribution and temporal range of Chinookan-Lower Columbia art forms, belongings, and associated exchange networks can help us better understand the Lower Columbia River regional dynamics of social change, group affiliation, group identity, and the histories of learned practices over many generations.
Previous research of ground stone tools and ground stone art belongings focused on stylistic differences observed by the naked eye, but my digital and multi-spectral techniques extend the range of optical imaging, thus providing a more detailed fine-grained analysis of the practices of groundstone production, trade, use, and discard.
This season I will conduct multi-spectral imaging and digital data collection (Technical Imaging, Ultraviolet Fluorescence, Infrared Reflectography, Visible-Induced Luminescence, Reflection Transformation Imaging, 3D photogrammetry). I will capture a collection of technical images with a modified digital camera sensitive to the spectral range of 360-860 nm to detect surface modifications such as paint preparation, evidence of use-wear, carving, and paint deterioration. These data allow me to examine the relationships and exchange networks of community art traditions, explore their connections to group identity, and analyze past land and resource use in the Lower Columbia River Region.
Expression of the 8.2 Kyr Event in Palau
Abstract: The relatively stable climate of the Holocene epoch (11.7 kyr BP-present) was punctuated by a period of large and abrupt climate change ca. 8.2 kyr BP, when an outburst of glacial meltwater into the Labrador Sea drove large and abrupt climate changes across the globe. However, little is known about the response of the tropical Pacific to this event. This project seeks to characterize the climatic expression of the 8.2 Kyr Event in Palau, western tropical North Pacific by measuring hydrogen isotope (2H/1H, 2H) ratios of microalgal lipids in sediments from Jellyfish Lake on the island of Merchecher and T-Lake on the island of Ngeruktabel. Since 2H values of microalgal lipids in the marine meromictic lakes of Palau have been shown to be sensitive recorders of rainfall we propose to produce a rainfall reconstruction with decadal-to-centennial resolution for the period 9-7 kyr BP. Sediment cores for this project were collected in 2013 and 2016 and initial core descriptions and radiocarbon chronologies have been generated. We hypothesize that the tropical rain band known as the Intertropical Convergence Zone (ITCZ) was driven south by the meltwater flood, as predicted by climate models, and that this resulted in a drying of Palau.
West Greenland coastal temperatures during the 8.2 ka event derived from alkenones
Abstract: The transition from the Last Glacial Maximum and deglaciation of the Laurentide Ice Sheet (LIS) was punctuated by a number of large and abrupt cooling periods (e.g., Younger Dryas (12.4 ka to 11.7 ka BP), the last of which occurred ca 8.2 ka BP. These abrupt cooling events are thought to have occurred when glacial-melt lakes along the LIS margin overtopped their moraines releasing massive volumes of freshwater into the Labrador Sea. Ice core records from atop the Greenland ice sheet show a relatively small decrease in temperatures (1-2˚C) over about two-hundred years but the magnitude of terrestrial changes along the coastal margin have not been documented. This project seeks to characterize the climatic impacts of the 8.2 ka event along the west coast of Greenland, by measuring the alkenone unsaturation index Uk’37 (based upon lipid molecules specific to certain phytoplankton of the phylum Haptophyta in sediments from Limnaea Sø, a closed-basin, oligohaline lake approximately ~100 km from the coast. A number of studies have demonstrated the temperature dependence of Uk’37 for lacustrine alkenones and Uk’37 has been used to develop records of past temperature from lake sediments. We propose to produce a temperature reconstruction with decadal-to-centennial resolution spanning the onset of the 8.2 ka event through the mid-Holocene. Sediment cores for this project were collected in 2012 and initial core descriptions and radiocarbon chronologies have been generated. We hypothesize that the magnitude of changes were significantly larger along the coastal margin of Greenland than the ice sheet summit due to local sea ice changes in the Labrador Sea/Baffin Bay, as predicted by climate models, and that this resulted in significantly greater cooling along coastal Greenland. Funds are sought from QRC to test this hypothesis and obtain the pilot data necessary to support a larger NSF proposal next year.
Evaluating the paleohydrologic potential of triple oxygen isotopes across a natural salinity gradient in tropical Pacific lake waters
Abstract: Paleohydrologic data provides important constraint on the climate system that cannot be inferred from the brief observational record. This project will test the efficacy of a new paleohydrologic proxy based on the triple oxygen isotope composition of lake water. Evaporation of an isolated water body leads to an increase in the concentration of the rare 18O isotope, and subtle changes of a few thousandths of a percent in the ratio of 17O to 18O relative to the Global Meteoric Water Line. Referred to as 17Oexcess, this quantity is distinct from existing paleohydrologic proxies in that it is very insensitive to temperature. A critical step in the development of a 17Oexcess paleohydrologic proxy is to demonstrate that closed lake systems behave in a manner similar to theory, and laboratory pan evaporation experiments. Doing so can be challenging over observable timescales because recent variations in the hydrologic balance of many lake systems are relatively subtle in comparison to the larger changes characterizing the Quaternary. The proposed work will solve this problem by examining 17Oexcess variability across a range of evaporative environments represented by the hundreds of independent, closed system lakes on the central tropical Pacific atoll of Kiritimati, which span salinities of <20 to >300‰. Results that suggest that environmental systems exhibit a relationship similar to that expected from theory and laboratory experiments will be used to pursue additional support from NSF’s P2C2 program for downcore measurements of 17Oexcess in tropical Pacific lacustrine carbonates. These downcore analyses have the potential to estimate past hydrologic variability in regions highly sensitive to the El Nino Southern Oscillation across at least the Holocene.
Rainshadow Effect on Stable Isotopes of n-Alkanes across the Cascade Mountains of Washington, USA
Abstract: The Cascade Mountains, which run north-south through Oregon and Washington into British Columbia, are one of the dominant geographic features of the Pacific Northwest. This project seeks to examine the stable-isotopic orographic rainshadow effect produced by the Cascades by comparing the d2H (dD) and d13C of n-alkanes (a long-chain hydrocarbon found in the waxy cuticles of plant leaves) from living plants, leaf detritus, and soil organic matter in a transect across the Cascades of Washington state. The dD of a plant is dominantly dependent on the dD of local rainfall, while the d13C depends mainly on the species of the plant and the aridity of its environment; the dD and d13C of n-alkanes in the soil depend on the plants which have contributed leaf litter to that soil. Documenting how the Cascade rainshadow affects and/or controls hydrogen and carbon isotopic trends is critical to understanding the fate of atmospheric moisture when it passes through orogens, and how plants (and soils) react to those changes. Moreover, understanding how isotopic trends evolve across the Cascade rainshadow is a mandatory step towards documenting the topographic evolution of the Cascades through geologic time via isotopic proxies. Identifying the nature of the isotopic trends – for instance, where and how transitions in isotopic composition occur – will allow us to determine if the degree and trend of isotopic depletion is directly correlated to rainshadow intensity and, by extension, the Cascades’ topography. This will provide a dataset for researchers studying isotopic distillation both by plants and by atmosphere dynamics, and a modern comparator for studies of ancient isotopic trends in this and similar settings.
Constraining material properties and age of Mima Mounds
Abstract: The Mima Mounds near Olympia, Washington are the archetype for similar appearing mounds around the world. This project seeks to better constraining the time for the formation of the mounding, as well as documenting the nature of the organic matter in the A horizon. An estimate of the time since the mounds have formed will be determined using cosmogenic Be-10. The exposure age of clasts in the center of a mound (shielded by 2+ m of A horizon material) will be compared to the exposure age of clasts from the inter-mound area at depth of a few decimeters. The exposure age will also help determine if the mounds are in a stable positions or if they are dynamically being rebuilt. The dark organic horizons are believed to be from black carbon that formed in the Mima Prairie as it was burned to facilitate the agricultural practices of the Native Americans for growing Camus species, a starch-rich plant that they actively harvested. The black carbon content will be estimated by chemical oxidation followed by Nuclear Magnetic Resonance to measure the aromatic content. To provide additional characterization, the organic matter in particular mounds that are dated by Be-10 and analyzed for black carbon, will be dated by C-14. The data will be interpreted in the context of the prevailing hypothesis of mound formation being formed by gophers. The Mima Mounds will be featured as an excursion for the Geological Society of America conference to be held in Seattle in October 2017, as well as presented in a talk at the memorial session for Steve Porter.
Permafrost distribution in High Andes
Abstract: We are developing a new tool to quantitatively map the extent of permafrost on a regional-scale. Our method uses satellite data and numerical modeling; in-situ measurements are essential to calibrate and validate our models. In 2017, QRC funded our successful expedition to the Ojos del Salados region of the Atacama, Andes, where we installed data loggers and thermistors at various depths, along with conducting a preliminary field survey. Since our first expedition, we analyzed satellite data and are developing models based on MODIS and other satellite data. The retrieval of hourly soil temperature data is critical for ground truthing and the development of our model delineating permafrost using remote sensed images. Furthermore, we will trench and survey in detail presence and depth of ground ice and water content for validation purposes.
The utility of palm phytoliths for inferring the evolution and paleoecology of Arecaceae
Palms (family Arecaceae) are ecologically important in a range of different tropical and subtropical ecosystems (e.g., rainforest, mangroves, savannas). We propose to study the utility of palm bio-silica bodies (phytoliths) for distinguishing palms from different taxonomic groups and with different ecologies (e.g., climate, habitat preference) in the fossil record. Being able to do so would enhance the ability of paleobotanists and archaeobotanists to (1) reconstruct the evolutionary history of palms, (2) infer ancient habitats and climates from fossil palm phytoliths in paleontological samples, and (3) track the domestication of palm species (e.g., Cocos nucifera, Phoenix dactylifera). Our approach is to measure phytolith shape and size variation in modern palm species from across the palm family using phytolith outlines obtained from confocal microscope images. We will test for phylogenetic signal, identify clade synapomorphies and examine correlations with habitat and climate.
The data produced by this study will be made available to the scientific community through a publication and through the online database of the Burke Museum, and will be of interest to scientists in all major fields of research at QRC.
A pilot geochemical analysis of food residues on ancient pottery from Kiwulan, Taiwan
Abstract: Our current knowledge of indigenous settlements in northeastern Taiwan suggests a relatively complex social system in the 17th century, around the same time as European contact (Chen 2007; Cheng 2008; Li 2014). I am investigating that whether European contact in this region stimulated a change in indigenous social organization by examining the archaeological evidence at the Kiwulan site (600 to 100 BP, i.e. AD 1400-1900), a major late Iron Age settlement in northeastern Taiwan (Chen 2007). In order to examine the social changes that occurred as a result of the European contact, I am comparing multiple lines of archaeological evidence between the pre-contact and post-contact periods.
This project proposes to further examine one of my foci, locally made pottery, which can reflect prehistoric socioeconomic patterns and enable me to explore the emergence of social inequality. I plan to test the hypothesis that European contact in northeastern Taiwan stimulated a change in social organization, which transformed food consumption at Kiwulan. My model predicts that one of the effects of social-economic inequality induced by European contact was greater differentiation of food consumption after European contact. I will use well-established isotope geochemistry methods to identify the types of foods stored in pots found at Kiwulan.