Earth Sciences Commons^™

Anthropogenic Controls On Overwash Deposition: Evidence And Consequences, Laura Rogers, Laura Moore, Evan Goldstein, Christopher Hein, Jorge Lorenzo Trueba, Andrew Ashton

Jorge Lorenzo-Trueba

Accelerated sea level rise and the potential for an increase in frequency of the most intense hurricanes due to climate change threaten the vitality and habitability of barrier islands by lowering their relative elevation and altering frequency of overwash. High-density development may further increase island vulnerability by restricting delivery of overwash to the subaerial island. We analyzed pre-Hurricane Sandy and post-Hurricane Sandy (2012) lidar surveys of the New Jersey coast to assess human influence on barrier overwash, comparing natural environments to two developed environments (commercial and residential) using shore-perpendicular topographic profiles. The volumes of overwash delivered to residential and commercial …

Natural And Human-Induced Variability In Barrier-Island Response To Sea Level Rise, Jennifer Miselis, Jorge Lorenzo Trueba

Jorge Lorenzo-Trueba

Storm-driven sediment fluxes onto and behind barrier islands help coastal barrier systems keep pace with sea level rise (SLR). Understanding what controls cross-shore sediment flux magnitudes is critical for making accurate forecasts of barrier response to increased SLR rates. Here, using an existing morphodynamic model for barrier island evolution, observations are used to constrain model parameters and explore potential variability in future barrier behavior. Using modeled drowning outcomes as a proxy for vulnerability to SLR, 0%, 28%, and 100% of the barrier is vulnerable to SLR rates of 4, 7, and 10 mm/yr, respectively. When only overwash fluxes are increased …

Exploring The Role Of Organic Matter Accumulation On Delta Evolution, Jorge Lorenzo Trueba, Vaughan Voller, Chris Paola, Robert Twilley, Azure Bevington

Jorge Lorenzo-Trueba

We explore the role of plant matter accumulation in the sediment column in determining the response of fluvial-deltas to base-level rise and simple subsidence profiles. Making the assumption that delta building processes operate to preserve the geometry of the delta plain, we model organic sedimentation in terms of the plant matter accumulation and accommodation (space made for sediment deposition) rates. A spatial integration of the organic sedimentation, added to the known river sediment input, leads to a model of delta evolution that estimates the fraction of organic sediments preserved in the delta. The model predicts that the maximum organic fraction …

Rollover, Drowning, And Discontinuous Retreat: Distinct Modes Of Barrier Response To Sea-Level Rise Arising From A Simple Morphodynamic Model, Jorge Lorenzo Trueba, Andrew Dale Ashton

Jorge Lorenzo-Trueba

We construct a simple morphodynamic model to investigate the long-term dynamic evolution of a coastal barrier system experiencing sea-level rise. Using a simplified barrier geometry, the model includes a dynamic shoreface profile that can be out of equilibrium and explicitly treats barrier sediment overwash as a flux. With barrier behavior primarily controlled by the maximum potential overwash flux and the rate of shoreface response, the modeled barrier system demonstrates four primary behaviors: height drowning, width drowning, constant landward retreat, and a periodic retreat. Height drowning occurs when overwash fluxes are insufficient to maintain the landward migration rate required to keep …

Effectiveness Of Four Water-Bearing Zones Of The Glacierized Basin In Meltwater Runoff Modeling, Umesh K. Haritashya

Umesh K. Haritashya

Meltwater runoff modeling from glacierized basins needs several input data, including total meltwater contributing area. This study utilizes optical remote sensing data to assess glacierized basins in the central Himalayas where snow and glaciers contribute substantially to the water resources. Result shows that there are four main water-bearing zones in the basin: (a) dry snow, (b) wet snow, (c) exposed glacial ice, and (d) debris-covered glacial ice, and it is possible to differentiate and map these zones and their spatio-temporal variations from satellite sensor data. These zones can then be incorporated in meltwater runoff modeling as separate entities because they …

Effects Of Changes In Moisture Source And The Upstream Rainout On Stable Isotopes In Precipitation – A Case Study In Nanjing, Eastern China, Y. Tang, H. Pang, W. Zhang, Y. Li, Shuang-Ye Wu, S. Hou

Shuang-ye Wu

In the Asian monsoon region, variations in the stable isotopic composition of speleothems have often been attributed to the "amount effect". However, an increasing number of studies suggest that the "amount effect" in local precipitation is insignificant or even non-existent. To explore this issue further, we examined the variability of daily stable isotopic composition (δ18O) in precipitation from September 2011 to November 2014 in Nanjing, eastern China. We found that intra-seasonal variations of δ18O during summer were not significantly correlated with local rainfall amount but could be linked to changes in the moisture source location and rainout processes in the …

Reconstruction Of The Hirnantian (Late Ordovician) Palaeotopography In The Upper Yangtze Region, Linna Zhang, Junxuan Fan, Qing Chen, Shuang-Ye Wu

Shuang-ye Wu

Reconstruction of the Hirnantian (Late Ordovician) palaeotopography in South China is important for understanding the distribution pattern of the Hirnantian marine depositional environment. In this study, we reconstructed the Hirnantian palaeotopography in the Upper Yangtze region based on the rankings of the palaeo-water depths, which were inferred according to the lithofacies and biofacies characteristics of the sections. Data from 374 Hirnantian sections were collected and standardized through the online Geobiodiversity Database. The Ordinary Kriging interpolation method in the ArcGIS software was applied to create the continuous surface of the palaeo-water depths, i.e. the Hirnantian palaeotopography. Meanwhile, the line transect analysis …

Transition From Contraction To Extension In The Northeastern Basin And Range: New Evidence From The Copper Mountains, Nevada, Jeffrey M. Rahl, Allen J. Mcgrew, Kenneth A. Foland

Allen J. McGrew

New mapping, structural analysis, and 40Ar/39Ar dating reveal an unusually well‐constrained history of Late Eocene extension in the Copper Mountains of the northern Basin and Range province. In this area, the northeast‐trending Copper Creek normal fault juxtaposes a distinctive sequence of metacarbonate and granitoid rocks against a footwall of Upper Precambrian to Lower Cambrian quartzite and phyllite. Correlation of the hanging wall with footwall rocks to the northwest provides an approximate piercing point that requires 8–12 km displacement in an ESE direction. This displaced fault slice is itself bounded above by another normal fault (the Meadow Fork Fault), which brings …

Prevailing Weather Conditions During Summer Seasons Around Gangotri Glacier, Pratap Singh, Umesh K. Haritashya, K. S. Ramasastri, Naresh Kumar

Umesh K. Haritashya

Meteorological data collected near the snout of the Gangotri Glacier suggest that the study area receives less rainfall. The average seasonal rainfall is observed to be about 260 mm. The rainfall distribution does not show any monsoon impact. Amount of seasonal rainfall is highly variable (131.4-368.8 mm) from year to year, but, in general, August had the maximum rainfall. A verage daily maximum and minimum temperatures were 14.7 and 4.1°C respectively, whereas average mean temperature was 9.4°C. July was recorded as the warmest month. During daytime, wind speed was four times higher than that at night-time. The average daytime and …

Multispectral Image Analysis Of Glaciers And Glacier Lakes In The Chugach Mountains, Alaska, Jeffrey Kargel, Matthew Beedle, Andrew Bush, Francisco Carreño, Elena Castellanos, Umesh Haritashya, Gregory Leonard, Javier Lillo, Ivan Lopez, Mark Pleasants, Edward Pollock, David Wolfe

Umesh Haritashya

The Chugach Mountains contain the largest nonpolar alpine glaciers in the world and include a wide variety of glacier types: some are land terminating; some calve variously into tidewater, lakes, and rivers; some are heavily debris covered; some are surge-type, whereas others are neither debris covered nor surge type. Nearly all are retreating, thinning, or both, though some rare ones are advancing, and some are thickening at high elevations. To assist the further documentation of changes, we establish an inventory of glaciers in the eastern Chugach Mountains. Several case studies of diverse glacier types showcase remotesensing applications and are used …

Encyclopedia Of Snow, Ice And Glaciers, Vijay P. Singh, Pratap Singh, Umesh K. Haritashya

Umesh K. Haritashya

The objective of this encyclopedia is to present the current state of scientific understanding of various aspects of earth’s cryosphere – snow, glaciers, ice caps, ice sheets, ice shelves, sea ice, river and lake ice, and permafrost – and their related interdisciplinary connections under one umbrella. Therefore, every effort has been made to provide a comprehensive coverage of cryosphere by including a broad array of topics, such as the atmospheric processes responsible for snow formation; snowfall observations; snow cover and snow surveys; transformation of snow to ice and changes in their properties; classification of ice and glaciers and their worldwide …

Field Validation Of Dem And Gis Derived Longitudinal Stream Profiles, Kathryn Schroeder, Eric Peterson, Toby Dogwiler

Eric Wade Peterson

Longitudinal stream profiles provide valuable information concerning geomorphic features and energy states in a stream. Traditionally, stream profiles have been generated by field surveying or topographic map analysis. The continued growth of digital data and Geographic Information Systems (GISs) provide another method by which to achieve stream profile generation. This work examines the effectiveness of digital data, digital elevation models (DEM), and GIS to construct stream profiles. To determine the most effective and accurate data for profile generation, profiles were created using 1-meter (1-m) and 3-meter (3-m) DEMs developed from LiDAR data. Additionally, stream profiles were created from unfilled DEMs …

Longitudinal Profile And Sediment Mobility As Geomorphic Tools To Interpret The History Of A Fluviokarst Stream System, John Woodside, Eric Peterson, Toby Dogwiler

Eric Wade Peterson

The complex drainage systems within karst settings can result in atypical longitudinal profiles. Features, such as cave entrances, can be expressed as anomalous ‘bumps’ in the longitudinal profile of a stream if downcutting has continued upstream of the area in which the water is pirated to the subsurface. Horn Hollow, a fluviokarst valley located in Carter Caves State Park Resort in northeastern Kentucky, was examined for these types of features. The objectives of this study were to determine if sediment mobility can be used as a proxy for anomalous areas along the profile of the valley and if detailed cross-sections …

Rock Strength Along A Fluvial Transect Of The Colorado Plateau - Quantifying A Fundamental Control On Geomorphology, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

Bedrock strength is a key parameter that influences slope stability, landscape erosion, and fluvial incision. Yet, it is often ignored or indirectly constrained in studies of landscape evolution, as with the K erodibility parameter in stream-power models. Empirical datasets of rock strength suited to address geomorphic questions are rare, in part because of the difficulty in measuring those rocks at Earth's surface that are heterolithic, weak, or poorly exposed. Here we present a large dataset of measured bedrock strength organized by rock units exposed along the length of the trunk Green–Colorado River through the iconic Colorado Plateau of the western …

A 70 Year History Of Coastal Dune Migration And Beach Erosion Along The Southern Shore Of Lake Michigan, Zoran Kilibarda, Craig Shillinglaw

Zoran Kilibarda

A study of aerial photographs from the Indiana Dunes National Lakeshore (adjacent to Michigan City, Indiana, United States of America) revealed that from 1938 to 2008 the Lakeshore’s Mount Baldy dune advanced inland 135 m, at an average rate of 1.9 m/year, while the beach north of the dune receded 98 m, at an average rate of 1.4 m/year. The highest rates of Mount Baldy dune movement (3.3 m/year) occurred concurrently (1965–1973) with highest rates of beach erosion (7.2 m/year). The lowest rates of Mount Baldy dune movement (0.3 m/year) occurred in 1958–1965 period. The highest rates of beach accretion …

Magnitude Of Floods And Its Consequences In Puthimari River Basin Of Assam, India, Pankaj Roy

Pankaj Roy

The Role Of Extratropical Cyclones In Shaping Dunes Along Southern And Southeastern Lake Michigan, Brian Yurk, Edward Hansen, Suzzanne Devries-Zimmerman, Zoran Kilibarda, Deanna Van Dijk, Brian Bodenbender, A. Krehel, T. Pennings

Zoran Kilibarda

This study investigates the impacts of extratropical cyclones on Lake Michigan dune complexes by integrating fi eld measurements and meteorological data from sites along the southeastern shore. Surface changes and wind velocities were monitored at Hoffmaster State Park, Saugatuck Harbor Natural Area, and Mount Baldy at Indiana Dunes National Lakeshore from October to April in 2010–2011 and 2011–2012. Over 70% of the events with wind speeds at least two standard deviations above the mean were associated with extratropical cyclones. The wind directions depended on the cyclone path, with westerly or southerly components most common. Local conditions moderated the effects of …

Sediment Impacts Of Removal Of A Low-Head Dam On A Sand Bedload River, Ottawa River, Ohio, James E. Evans

James E. Evans

No abstract provided.

Using The Longitudinal River Profile Of The Rio San Jose And 40ar/39ar Dating Of Late-Cenozoic Basalts To Test Models For Mantle-Driven Uplift Across The Jemez Lineament, New Mexico, Mike Channer, Jason Ricketts, Matt Zimmerer, Matt Heizler, Karl Karlstrom

Mike Channer

Mantle-driven differential uplift has been proposed to contribute to dynamic typography in the western United States. Neogene and ongoing mantle flow is postulated to be driven by upper mantle convection and to cause subtle broad-scale differential uplift that affects surface topography. This study focuses on the possible connection between mantle convection and surface topography along the Jemez lineament in New Mexico and is motivated by tomographic images from the EarthScope experiment that show this zone is underlain by low-velocity mantle that potentially could drive uplift. To test this possible connection, we constructed a longitudinal profile of the Rio San Jose …

The Effects Of Surface Water Velocity On Hyporheic Interchange, Timothy Sickbert, Eric Wade Peterson

Eric Wade Peterson

When evaluating hyporheic exchange in a flowing stream, it is inappropriate to directly compare stream stage with subsurface hydraulic head (h) to determine direction and magnitude of the gradient between the stream and the subsurface. In the case of moving water, it is invalid to ignore velocity and to assume that stage equals the net downward pressure on the streambed. The Bernoulli equation describes the distribution of energy within flowing fluids and implies that net pressure decreases as a function of velocity, i.e., the Venturi Effect, which sufficiently reduces the pressure on the streambed to create the appearance of a …

Bedrock Strength And River Morphology Datasets For The Colorado River System, Natalie Bursztyn, Joel Pederson

Natalie Bursztyn

There has been renewed debate over the mechanisms and timing of both uplift and erosion in the Interior West. Yet, in order to understand the region’s long-term landscape evolution and patterns of topography a third factor of bedrock properties must be considered. We are completing a large dataset of bedrock strength and exploring it in the context of reach-scale topographic metrics for the upper Colorado River system. Included are rock-strength measures such as laboratory tensile strength, Schmidt-hammer compressive strength, approximate shale proportion, and Selby rock mass strength classification. To estimate the strength of units too incompetent to test directly, such …

Formation, Deformation, And Incision Of Colorado River Terraces Upstream Of Moab, Utah, Andrew Jochems

Andrew Jochems

Fluvial terraces contain information about incision, deformation, and climate change. In this study, a chronostratigraphic record of Colorado River terraces is constructed from optically stimulated luminescence (OSL) dating of Pleistocene alluvium and real-time kinematic (RTK) GPS surveys of terrace form. This record is analyzed to relate terrace formation to late Pleistocene climate fluctuations, and terrain analyses and longitudinal profile patterns reveal recent salt-related activity in the northern Paradox Basin as well as patterns in Colorado Plateau incision.

A well-preserved, correlative suite of mainstem (M) fluvial deposits exists along the Colorado River upstream of Moab, Utah. Absolute dates indicate sedimentation >70 …

Exhumation Of The Southern Sierra Nevada–Eastern Tehachapi Mountains Constrained By Low-Temperature Thermochronology: Implications For The Initiation Of The Garlock Fault, Ann Blythe, N Longinotti

Ann Blythe

New apatite and zircon fission-track and apatite (U-Th)/He data from nine samples collected on a north-south transect across the southern Sierra Nevada–eastern Tehachapi Mountains constrain the cooling and exhumation history over the past ∼70 m.y. The four northernmost samples yielded zircon and apatite fission-track ages of ca. 70 Ma, indicating rapid cooling from ∼250 °C to <60 °C (6–8 km of exhumation) at that time. Four of the five southernmost samples yielded slightly younger zircon fission-track ages (57–46 Ma) and apatite fission-track ages (21–18 Ma); the fifth southern sample (from a lower elevation) yielded an apatite fission-track age of ca. 11 Ma. Eight of the nine samples yielded apatite (U-Th)/He ages; these ranged from 60 to 9 Ma, with the youngest ages from the southernmost samples. Inverse thermal history models developed from the data reveal two major stages of cooling for the area, with an initial major cooling event ending at ca. 70 Ma, followed by 50 m.y. of thermal stasis and a second major cooling event beginning at 20 Ma and continuing to the present. The data are consistent with northward-directed tilting and exhumation beginning at 20 Ma, probably as the result of north-south extension in the Mojave Desert on an early strand of the Garlock fault with down-to-the-south offset. A third minor phase of rapid exhumation beginning at ca. 10 Ma is suggested by the data; this may indicate the beginning of left-lateral slip on the Garlock fault.

Meteoric 10Be, FeD, And Clay In Critical Zone Soils, Front Range, Colorado, Cianna Wyshnytzky, James Mccarthy

Cianna E Wyshnytzky

The critical zone is the zone within which meteoric water, atmospheric gases, soil, and bedrock interact, encompassing the zone of soil formation (Anderson et al., 2007). The concentrations of various pedogenic compounds at a given location indicate the degree of weathering that has taken place in the Critical Zone. Among the products of chemical weathering are secondary phyllosilicate minerals (clays) and iron (Birkeland, 1999). At stable sites, chronosequence studies have shown that the amount of pedogenic iron oxide and clay increase as soils become older (McFadden and Hendricks, 1985).

Meteoric ¹⁰Be is a cosmogenic nuclide produced from oxygen and nitrogen …

Updated Glacial Chronology Of The South Fork Hoh River Valley, Olympic Peninsula, Washington Through Detailed Stratigraphy And Osl Dating, Cianna E. Wyshnytzky, Tammy M. Rittenour, Glenn D. Thackray

Cianna E Wyshnytzky

Four glacial advances are preserved and exposed in the stratigraphy of the South Fork Hoh River valley. The oldest of these advances extended beyond the South Fork valley into the Hoh River valley. The three younger advances are preserved in the stratigraphy cut bank exposures in the valley and geomorphically by moraines and outwash plains. One of these advances represents a re-advance to the same terminal position of the previous advance and has not previously been recognized in this valley or other glaciated valleys in the western Olympic Mountains. This finding advocates for a detailed sedimentologic and stratigraphic approach to …

Holocene Sediment Distribution On The Inner Continental Shelf Of Northeastern South Carolina: Implications For The Regional Sediment Budget And Long-Term Shoreline Response, Jenny Denny, William Schwab, Wayne Baldwain, Walter Barnhadt, Paul Gayes, Robert Morton, John Warner, Neil Driscoll, George Voulgaris

George Voulgaris

High-resolution geophysical and sediment sampling surveys were conducted offshore of the Grand Strand, South Carolina to define the shallow geologic framework of the inner shelf. Results are used to identify and map Holocene sediment deposits, infer sediment transport pathways, and discuss implications for the regional coastal sediment budget.

The thickest deposits of Holocene sediment observed on the inner shelf form shoal complexes composed of moderately sorted fine sand, which are primarily located offshore of modern tidal inlets. These shoal deposits contain ∼67 M m3 of sediment, approximately 96% of Holocene sediment stored on the inner shelf. Due to the lack …

Classification Of The Alterations Of Beaver Dams To Headwater Streams In Northeastern Connecticut, U.S.A., Denise Burchsted, Melinda D. Daniels

Denise Burchsted

Of the many types of barriers to water flow, beaver dams are among the smallest, typically lasting less than a decade and rarely exceeding 1.5 m in height. They are also among the most frequent and common obstructions in rivers, with a density often exceeding ten dams per km, a frequency of construction within a given network on a time scale of years, and a historic extent covering most of North America. Past quantification of the geomorphologic impact of beaver dams has primarily been limited to local impacts within individual impoundments and is of limited geographic scope. To assess the …

Sea-Cliff Erosion With Rising Sea-Level Along Shores Exposing Glacial Material In Atlantic Canada, Eric R. Force

Eric R Force

Rapid retreat rates of sea cliffs exposing glacial material are a widespread problem, especially in Atlantic Canada, and one that will continue. Prediction of retreat rates at specific sites involves many variables, but a factor that has commonly been overlooked in such prediction is the slope of the bedrock surface under the glacial material. A glaciated bedrock platform is generally necessary to establish a stable situation of temporary equilibrium, and as sea- level rises, the bedrock slope determines the location of the new equilib- rium position. An example from Nova Scotia shows that bedrock slope is so low on some …

The Shortcomings Of "Passive" Urban River Restoration After Low-Head Dam Removal, Ottawa River (Northwestern Ohio, U.S.A.): What The Sedimentary Record Can Teach Us, James E. Evans

James E. Evans

No abstract provided.

Recalibrating Aeolian Sand Transport Models, Douglas Sherman, Bailiang Li, Jean Ellis, Eugene Farrell, Luis Maia, Helena Granja

Jean Taylor Ellis

No abstract provided.