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Modern Coastal Systems
Modern Coastal Systems
Tidal channels connect estuarine waters to landward salt marshes, and drive the geomorphologic evolution of tidal flats by acting as essential drainage pathways for exchanging water, sediments, and nutrients. Vegetation is known to stabilize tidal boundaries and alter channel network configurations, but biofilms (bacteria and algae encased in a sticky extra polymeric substrate) may also impact the organization of channels by altering sediment erodability. This field-based study uses Structure from Motion techniques (from drone imagery) to build 3D reconstructions of tidal flats, as well as state of the art instruments like the Gust Erosion chamber to perform in-situ test of the erodability of sediment. We have demonstrated the ecogeomorphic relationship between seasonal biofilms and increased sediment stability on tidal flats, so now I am working to understand how this interaction may prompt channel migration and/or the development of complex channnel networks which could lead to more efficient drainage of water and sediment in Willapa Bay.
Adapted from van de Vijsel et a., 2023
King et al., 2024
Ancient Sea-Level Change
Ancient Sea-Level Change
Predictions of future sea-level change and ice sheet stability rely on estimates of sea level during past warm periods such as the mid-Pliocene Warm Period (MPWP; 3.264 – 3.025 Ma). I calculated the first ‘viscoelastic’ sea-level fingerprints derived from individual Pliocene ice sheets (North America, Greenland, Eurasia, West Antarctica, and the Wilkes Basin, Aurora Basin, and Prydz Bay Embayment in East Antarctica). These fingerprints allowed me to explore the inherent spatial biases associated with the few geographic locations that contain physical archives of Pliocene sea-level change. My results indicate that, of these geographic locations, no single field site can provide an unbiased constraint on the amplitude or sources of ice melt during this period. Instead, combinations of observations are needed to yield a stronger constraint (King et al., 2024).
Stratigraphic Modeling
Stratigraphic Modeling
Glacial isostatic adjustment (GIA) is the gravitational and viscoelastic deformation of Earth’s crust in response to the loading and unloading of ice sheets and oceans. GIA affects the preservation of the number, magnitude, and timing of sea-level change in Quaternary siliciclastic continental shelf stratigraphic records. While most studies acknowledge the possible distortion of local accommodation from tectonics and sedimentation, no study to date has explored how geographic variation in sea level induced by GIA manifests in stratigraphy. I developed the first stratigraphic forward model that utilizes realistic Quaternary time-series of GIA-impacted sea level and stochastic sedimentation to build synthetic stratigraphic records. I found that continental shelf stratigraphic records preserve glacial-interglacial sea-level change differently depending on the distance from a former ice sheet and its peripheral bulge, leading to difficulties in accurate correlations between records (King and Creveling, 2022).
King & Creveling, 2022
Created by Meghan E. King
Abandoned Channel Stratigraphy
Abandoned Channel Stratigraphy
Meandering channel avulsion and subsequent depositional fill offer sedimentological insights into past environmental conditions on high elevation floodplains. I used aerial imagery and the stratigraphy of abandoned channels on the East River, Colorado to understand post-avulsion depositional processes, which can affect the retention and distribution of carbon, nutrients, and contaminants within floodplains.
Precambrian Reefs
Precambrian Reefs
Shallow-water reef environments serve as the loci of the earliest evidence of life in the rock record, and owing to their high origination rates, may even be considered “cradles of evolution”. In contrast with most modern reefs that are built by metazoans, Precambrian (i.e., older than 533 Mya) systems were dominated by microbially-mediated structures. I worked on a series of projects that addressed (1) the first appearance of sponges in Precambrian reefs of the Little Dal group, (2) the existence and morphology of stromatolite built spur-and-groove features in Precambrian reefs of the Great Slave Lake Supergroup.
Created by A. Anders Larson Tevis
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