About
235
Publications
46,079
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
9,274
Citations
Citations since 2017
Publications
Publications (235)
The fluvial sedimentary record is largely composed of deposits from relatively common flow events, rather than more catastrophic scour-and-fill events. At the scales of bedforms, such deposits are preserved within the stratigraphic record because they rapidly accumulate within, and are protected by, morphodynamic topographic depressions that occur...
A proposed null hypothesis for fluvial terrace formation is that
internally generated or autogenic processes, such as lateral migration and
river-bend cutoff, produce variabilities in channel incision that lead to the
abandonment of floodplain segments as terraces. Alternatively, fluvial
terraces have the potential to record past environmental chan...
Flood dynamics in low-relief landscapes control the lateral exchange of water and sediment between a river and its floodplain. Locations where these exchanges occur for any given river discharge depend on local bank elevations, which in turn depend on the type of landform present immediately adjacent to the river channel. Our analysis separated lan...
Interpretation of deep‐water channel deposits is challenging because the spatial arrangement of their constituent lithologies is highly variable. This variability is often thought to be a signature of complex interactions between controlling boundary conditions and processes. A three‐dimensional forward stratigraphic model of a sinuous meandering c...
Hydrologic connectivity controls the lateral exchange of water, solids, and solutes between rivers and floodplains, and is critical to ecosystem function, water treatment, flood attenuation, and geomorphic processes. This connectivity has been well‐studied, typically through the lens of fluvial flooding. In regions prone to heavy rainfall, the timi...
Understanding the detailed structure of landscape topography is important when assessing risks in coastal plain areas susceptible to the combined effects of fluvial, pluvial and coastal flooding. Key to this analysis is the identification and characterization of drainage basins that control surface water flow, but the factors controlling the format...
The windward islands of the Lucayan Archipelago (Bahamas) form an Atlantic Ocean– facing transect spanning >950 km in length and 6° of latitude. The islands’ topography is largely constructed from carbonate wind-blown dunes (i.e., aeolianites) deposited during the interglacial phases of the Late Pleistocene and Holocene. New digital elevation data...
A proposed null hypothesis for fluvial terrace formation is that internally generated or autogenic processes such as lateral migration and river-bend cutoff produce variabilities in channel incision that lead to the abandonment of floodplain segments as terraces. Alternatively, fluvial terraces have the potential to record past environmental change...
It is well established that sedimentary margins grow by sediments bypassing through shelf- and slope-incising canyons onto the basin floor and by sediments being deposited incrementally across clinoforming and prograding margins. However, we argue that these two distinctive types of deep-water sediment supply to the basin floor and to the margin ar...
A time series of aerial images of a dune field on a migrating free bar in the North Loup River, Nebraska, is used to generate a quantified dataset that allows analyses of crestline deformation, dune interaction type and spatial density, and impact of spurs. Measurement of dune parameters show that the dune field maintained a dynamic steady-state pa...
Innovative science benefits from diversity of thought and influence at all waypoints along the scientific journey, from early education to career-length contributions in research and mentorship. Scientific societies, like the Society for Sedimentary Geology (SEPM), steward their innovators and the direction of the science, thereby defining the soci...
Connecting real-time measurements of current–bed interactions to the temporal evolution of submarine channels can be extremely challenging in natural settings. We present a suite of physical experiments that offer insight into the spectrum of interactions between turbidity currents and their channels, from i) detachment-limited erosion to ii) trans...
Many published interpretations of ancient fluvial systems have relied on observations of extensive outcrops of thick successions. This paper, in contrast, demonstrates that a regional understanding of palaeoriver kinematics, depositional setting and sedimentation rates can be interpreted from local sedimentological measurements of bedform and barfo...
Understanding how delta islands grow and change at contemporary, interannual timescales remains a key scientific goal and societal need, but the high-resolution, high frequency morphodynamic data that would be most useful for this are as yet logistically prohibitive. The recorded water levels needed for relative elevation analysis are also often la...
Subsidence alone is often too slow to provide the necessary relief to preserve channel belts continuously over 10s of km, as is often observed in outcrop on Earth and Mars, as well as subsurface seismic volumes. A significant source of topographic relief was recently recognized along coastal plains of the US Gulf of Mexico and Atlantic, regions gen...
Significance
Fine-grained sediment transport systems (grain size under 2,000 μm) are ubiquitous over time and space on Earth and extraplanetary surfaces, and include rivers, deltaic coastal settings, and submarine, lahar, and subglacial systems. Forecasting the evolution of Earth’s surface requires a predictive algorithm for sediment transport. Her...
The distribution of cross‐set thicknesses is important data for reconstructing ancient aeolian dune fields from the strata they accumulated, but most aeolian strata on Mars must be observed from satellite. We hypothesize that remote sensing resolution limits will affect cross‐set thickness measurements and the dune‐field reconstructions that follow...
In this paper we use multiple field surveys spanning several decades to systematically evaluate the geomorphic consequences of a change in flow hydraulics from uniform flow to backwater flow for the Lower Trinity River in east TX, USA. Spatial changes in lateral migration rate, channel geometry, and point bar size correspond with two distinct geomo...
Comparison of three bare-earth lidar data sets along 30 consecutive river bends on the Trinity River in Texas, USA, shows that differential migration of river banks in a channel bend counterbalances past bank migrations so that a statistically steady-state channel width is maintained. Two difference maps created from lidar flown in 2011, 2015, and...
The distribution of cross-set thicknesses is important field-collected data for reconstructing ancient aeolian dune fields from the strata they accumulated, but most aeolian strata on Mars must be observed with remote sensing. We hypothesize that remote sensing resolution limits will affect cross-set thickness measurements and the dune field recons...
A reduced-complexity aeolian dune stratification model is developed and applied to explore the role of dune morphodynamics in the creation of synthetic sections of aeolian stratigraphy originating from three sets of environmental forcing: 1) steady wind transport capacity, 2) steady bed aggradation and variable wind transport capacity, and 3) stead...
The geometry of river-channel belts is shaped by the migration, aggradation, and avulsion of associated rivers, which is controlled by the motion of bedforms and barforms. The motion of bedforms and barforms can be reconstructed using the geometry and preservation of their associated strata. In order to reconstruct the kinematics of the ancient Ced...
The stratigraphic architecture of aeolian sandstones is thought to record signals originating from both autogenic dune behavior and allogenic environmental boundary conditions within which the dune field evolves. Mapping of outcrop-scale surfaces and sets of cross-strata between these surfaces for the Jurassic Page Sandstone near Page, Arizona, USA...
In shallow marine environments gravity-driven currents (e.g., hyperpycnal flows) often traverse surface wave fields, and the resulting complex flows are key mechanisms for offshore sediment transport. Our laboratory experiments illustrate how surface waves alter sediment transport in gravity-driven density currents. The addition of a wave field to...
Scroll bars across a 65‐kilometer stretch of the Trinity River in Texas, USA, were studied using lidar data as well as with a series of 11 trenches spread out across the survey area. We conclude that scroll bars are levees that are deposited along the inner banks of these meandering river bends. Scroll bar crests were found to have similar elevatio...
Clean basal and capping argillaceous sandstone couplets in deep water settings have been previously interpreted as the result of spatially segregated turbidity currents and debris flows or spatio‐temporal transitioning of a turbulent flow to a transitional/laminar state. However, this paper presents three‐dimensional laboratory experiments demonstr...
The surface of Mars preserves a record of more than 200 paleolakes that are breached and drained by outlet canyons. Here we present observations of outlet breach and canyon geometry for a subset of these basins (n = 24). We show that the volume of water drained during breach formation is a significant predictor of breach depth and cross-sectional a...
The stratigraphic architecture of aeolian sandstones is thought to record signals originating from both autogenic dune behavior and allogenic environmental boundary conditions within which the dune field evolves. Mapping of outcrop-scale surfaces and sets of cross-strata between these surfaces for the Jurassic Page Sandstone near Page, Arizona, USA...
A reduced complexity aeolian dune stratification model is developed and applied to explore the role of dune morphodynamics in the creation of synthetic sections of aeolian stratigraphy originating from three sets of environmental forcing: 1) steady wind transport capacity, 2) steady bed aggradation and variable wind transport capacity, and 3) stead...
Connecting real time measurements of current-bed interactions to the temporal evolution of submarine channels can be extremely challenging in natural settings. We present a suite of physical experiments that offer insight into the spectrum of interactions between turbidity currents and their channels, from (i) detachment-limited erosion to (ii) tra...
Fluvial channels encounter a backwater reach when they approach a standing body of water, and recent studies have shown that the transition from normal flow to backwater-influenced flow is associated with sediment mass extraction through deposition. Here we test the hypothesis that systematic changes in the geometry of channel-belt deposits and sed...
Recent work at Aeolis Dorsa, Mars has identified exposure of fluvial sedimentary outcrop deposited early in martian history, likely during the late Hesperian or earlier. Here, we examine a ∼1200 km² exposure of sedimentary outcrop in southeast Aeolis Dorsa. Total thickness of the stratigraphic section exceeds 100 m. We identify eight discrete compl...
The Middle Jurassic Todilto Member of the Wanakah Formation is a carbonate and gypsum unit inset into the underlying aeolian Entrada Sandstone in the San Juan Basin. Field and thin section study of the uppermost Entrada and Todilto at Ghost Ranch, New Mexico, identified Todilto facies and their relationship to remnant Entrada dune topography. Resul...
Sadler's (1981) analysis of how measured sedimentation rate decreases with timescale of measurement quantified the vanishingly small fractional time preservation-completeness-of the stratigraphic record. Generalized numerical models have shown that the Sadler effect can be recovered, through the action of erosional clipping and time removal (the "s...
Time-lapse airborne lidar on the coastal Trinity River in Texas, USA, shows profound downstream variability in point bar growth and cut bank erosion resulting from a historically large flood that occurred in 2015. The difference map generated from two surveys covers 55 river bends and captures the transition from quasi-uniform flow into backwater f...
The validation of numerical models is an important component of modeling to ensure reliability of model outputs under prescribed conditions. In river deltas, robust validation of models is paramount given that models are used to forecast land change and to track water, solid, and solute transport through the deltaic network. We propose using transf...
A study of the Lower Miocene Fleming Group in Refugio County, Texas from 3-D seismic and wireline-log data documents continuous strandplain and associated lower-coastal-plain fluvial systems along a wave-dominated shoreline. This study delineates and characterizes, through the interpretation of seismic attributes and seismic geomorphology maps from...
The Jezero crater open-basin lake contains two well-exposed fluvial sedimentary deposits formed early in martian history. Here, we examine the geometry and architecture of the Jezero western delta fluvial stratigraphy using high-resolution orbital images and digital elevation models (DEMs). The goal of this analysis is to reconstruct the evolution...
Aeolis Dorsa, a large sedimentary basin on Mars, contains an array of fluvially dominated sedimentary deposits. These deposits preserve a record of fluvial erosion and deposition during early Martian history. We present evidence that some of these fluvial deposits represent incised valleys carved and filled during falls and rises in base level, whi...
The formative conditions for bedform spurs and their roles in bedform dynamics and associated sediment transport are described herein. Bedform spurs are formed by helical vortices that trail from the lee surface of oblique segments of bedform crestlines. Trailing helical vortices quickly route sediment away from the lee surface of their parent bedf...
Coastal wetland systems are among the most dynamic landscapes on Earth's surface; however, interrelated processes create wetland platforms that are relatively constant in space and time. Theoretically, ‘stable’ elevations should maintain themselves through time if the balance of processes creating that elevation remains unchanged. At Louisiana's pr...
Recent studies of sediment-gravity flows and their deposits have highlighted the importance and complexity of turbidity currents interacting with water-surface waves. We investigate whether turbidity currents can transport an oscillatory flow field generated by water-surface waves into deeper water. A set of experiments have been designed to answer...
Fluvial channels encounter a backwater reach when they approach a standing body of water, and recent studies have shown that the transition from normal flow to backwater-influenced flow is associated with
sediment mass extraction through deposition. Here we test the hypothesis that systematic changes in the geometry of channel-belt deposits and sed...
Although recent work has shown that changing interstitial fluid density within turbidity currents is a frequently overlooked factor affecting the texture and internal architecture of turbidites, little is known about its influence on submarine fan morphology. Here we present the results of three-dimensional flume experiments of turbidity currents t...
A surface model for aeolian bedform topography is adapted from a surface model of subaqueous bedform topography. The aeolian bedform surface model is developed using a uniform grid with a cell-centered finite volume approximation of the sediment continuity equation. The resulting modeling framework approximates the dynamic motions of aeolian bedfor...
Shallow coastal regions are among the fastest evolving landscapes but are notoriously difficult to measure with high spatiotemporal resolution. Using Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data, we demonstrate that high signal-to-noise L band synthetic aperture radar (SAR) can reveal subaqueous channel networks at the distal e...
Aeolian dune motion is thought to be driven by an annual cycle of sediment-transporting wind events. Each wind event drives uneven motion of dune crestlines, yet dune crestlines align as a trend to an annual cycle of wind. Understanding the variability in dune motion over such a cycle aids the interpretation of aeolian cross-stratification, often a...
Crater basins on Mars host thick sedimentary sequences, which record the environments of early Mars. These basin fills commonly exhibit mound morphologies thought to arise from aeolian erosion of initially crater filling strata. This study presents transport-based models explaining how mounds could be carved by wind. Wind tunnel experiments generat...
The transition of flow between laterally confined channels and the unchannelized delta front controls the morphodynamic evolution of river deltas but has rarely been measured at the field scale. We quantify flow patterns and bathymetry that define the evolution of the subaqueous delta front on the Wax Lake Delta, a rapidly prograding delta in coast...
Three-dimensional seismic data is often used to visualize the interior of thick sediment accumulations. Channel belts, the composite deposits left behind by laterally mobile channels, are easy to identify in seismically-imaged deltaic and fluvial environments. A few key questions inevitably arise while mapping channel belts in seismic. Where was th...
The processes involved in the initiation of submarine channels on the upper continental slope are incompletely understood. We use observations from physical experiments to explore the boundary conditions that are important for the initiation of sub-aqueous slope channels by turbidity currents. We discuss the results of three physical experiments. T...
Decades of planetary exploration have revealed an abundance of geomorphic evidence for ancient fluvial activity on the surface of Mars; however, only in the past ~15 years have remote sensing data sets existed with the necessary resolution to study the details of the martian sedimentary rock record. Coastal transition zones are amongst the diverse...
Gradually varied flow occurs as a river approaches the coast, resulting in a hydraulic transition from quasi-normal flow to backwater flow within the channel. The hydraulic transition occurs in concert with changes to the channel’s geometry. In this presentation we describe and show a systematic evaluation of the geomorphic consequences of a change...
Paleo-flow and paleo-environmental reconstruction from ancient deposits is a critical task for earth surface scientists interested in the sedimentary record. Forming processes are commonly interpreted from the architectural characteristics of sedimentary deposits using quantitative relationships derived from experiments or geomorphic studies. Howev...
A goal of paleotsunami research is to quantitatively reconstruct wave hydraulics from sediment deposits in order to better understand coastal hazards. Simple models have been proposed to predict wave heights and velocities, based largely on deposit grain size distributions (GSDs). Although seemingly consistent with some recent tsunamis, little inde...
The geometry of rivers has been characterized in terms of downstream and at-a-station hydraulic geometry, based on individual cross-sections. Such analyses do not, however, provide insight as to how these cross-sections are connected. We generalize the concept of hydraulic geometry, using data on bathymetry from four reaches of meandering rivers th...
As with most dune fields, the White Sands Dune Field in New Mexico forms in a wind regime that is not unimodal. In this study, crescentic dune shape change (deformation) with migration at White Sands was explored in a time series of five lidar-derived digital elevation models (DEM) and compared to a record of wind direction and speed during the sam...
This paper presents a non-invasive acoustic reflection technique to visualize sediment-laden flows over a wide range of sediment concentrations (5–75% by volume) in the laboratory. A Panametrics V301-SU Immersion transducer with 0.5 MHz center frequency was used to generate acoustic reflections that were sampled at 10 MHz. The strength of this tech...
Late Pleistocene to Holocene Morava River valley-fill of the eastern Czech Republic reflects the geomorphic evolution of the valley as forced by climate change. Valley-fill stratigraphy was studied through measured sections, optically stimulated luminescence (OSL) and radiocarbon dating, ground-penetrating radar surveys of relict sand dunes, archiv...
Breaching is a type of retrogressive submarine slope failure associated with pore pressure drops in both space and time, and this drop strengthens the failing deposit. Breaching is characterized by a near-vertical failure surface that retreats with a relatively constant velocity, on the order of a millimeter per second. Breaching is controlled by i...
Constraining the depositional gradient of ancient alluvial river systems can aid in reconstructing landscapes and estimating paleodischarge by establishing boundaries on the climatic and tectonic history of continental sequences. We present three methods for estimating ancient depositional gradients based on the interpreted mode of sediment transpo...
Decoupling the preserved signal of environmental (allogenic) forcing from those of internally generated (autogenic) processes is at the centre of understanding the evolution of the Earth's surface preserved in the sedimentary record. A major stumbling block for distinguishing between allogenic versus autogenic signatures in the stratigraphic record...