scholarly journals Tidal Flat Depositional Response to Neotectonic Cyclic Uplift and Subsidence (1–2 m) as Superimposed on Latest-Holocene Net Sea Level Rise (1.0 m/ka) in a Large Shallow Mesotidal Wave-Dominated Estuary, Willapa Bay, Washington, USA

2018 ◽  
Vol 10 (1) ◽  
pp. 109 ◽  
Author(s):  
Curt D. Peterson ◽  
Sandy Vanderburgh
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tidal Flat ◽  
Late Holocene ◽  
Columbia River ◽  
Small Rivers ◽  
Intertidal Flat ◽  
Sedimentation Rates ◽  
Lateral Migration ◽  
Willapa Bay

The late-Holocene record of tidal flat deposition in the large shallow Willapa Bay estuary (43 km in length), located in the Columbia River Littoral Cell (CRLC) system (160 km length), was investigated with new vibracores (n=30) and gouge cores (n=8), reaching 2–5 m depth subsurface. Reversing up-core trends of muddy sand to peaty mud deposits in marginal tidal flat settings demonstrate episodic submergence events resulting from cyclic tectonic uplift and subsidence (1–2 m) in the Cascadia subduction zone. These short-term reversals are superimposed on longer-term trends of overall sediment coarsening-up, which represent the transgression of higher-energy sandy tidal flats over pre-existing lower-energy tidal flat mud and peaty mud deposits in late-Holocene time. Fining-up trends associated with channel lateral migration and accretionary bank deposition occurred only infrequently in the broad intertidal flats of Willapa Bay. Vibracores and gouge cores were dated by 14C (n=16) and paleo-subsidence event contacts (n=17). Vibracore median probability 14C ages ranged from 0 to 6,992 yr BP and averaged 2,174 yr BP. Dated sample ages and corresponding depths of tidal flat deposits yield net sedimentation rates of 0.9–1.2 m ka-1, depending on the averaging methods used. Net sedimentation rates in the intertidal flat settings (~1.0 m ka-1) are comparable to the rate of net sea level rise (~1.0 m ka-1), as based on dated paleo-tidal marsh deposits in Willapa Bay. Reported modern inputs of river sand (total=1.77x104 m3 yr-1), from the three small rivers that flow into Willapa Bay, fall well short of the estimated increasing accommodation space (1.9x105 m3 yr-1) in the intertidal (MLLW-MHHW) setting (1.9x108 m2 surface area) during the last 3 ka, or 3.0 m of sea level rise. The under-supply of tributary sand permitted the influx of littoral sand (1.1x105 m3 yr-1) into Willapa Bay, as based on the net sedimentation rate (~1.0 m ka-1) and textural composition (average 60 % littoral sand) in analyzed core sections (n=179). The long-term littoral sand sink in Willapa Bay’s intertidal setting (55 % of total estuary area) is estimated to be about 5 % of the Columbia River supply of sand to the CRLC system, and about 30% relative to the littoral sand accumulated in barrier spits and beach plains during late-Holocene time. A 2.0 m rise in future sea level could yield a littoral sand sink of 2.2x108 m3 in the Willapa Bay intertidal setting, resulting in an equivalent shoreline retreat of 600 m along a 50 km distance of the barrier spit and beach plains that are located adjacent to the Willapa Bay tidal inlet. Willapa Bay serves as proxy for potential littoral sand sinks in other shallow mesotidal estuary-barrier-beach systems around the world following future global sea level rise.

scholarly journals Late Holocene Geomorphology of the Columbia River Estuary, Oregon and Washington, USA

2014 ◽  
Vol 6 (2) ◽  
pp. 1 ◽  
Author(s):  
Curt Peterson ◽  
Sandy Vanderburgh ◽  
Michael C. Roberts
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Late Holocene ◽  
River Estuary ◽  
Columbia River ◽  
Sediment Supply ◽  
Sedimentation Rates ◽  
Lateral Migration ◽  
Columbia River Estuary ◽  
Apparent Paradox

Abundant river sediment supply and an open-water central bay area characterize the geomorphology of the large Columbia River estuary (~ 100 km in length). Lateral floodplains and marsh islands do constrict the uppermost reaches of the estuary, but the central axes of the lower estuary are dominated by shallow sand shoals (0–4 m water depth). A total of 58 vibracores are used to document the grain size and age (0–2,500 14CyrBP) of late Holocene deposits in the estuary. Sedimentation rates in stable floodplains (1.1 m ka-1) reflect rates of relative sea level rise (0.75 m ka-1). Sedimentation rates of muddy sand accretionary banks and prehistoric sand shoals (1.5–7 m ka-1) greatly exceed coeval rates of sea level rise, so they must represent short–term rates of vertical accretion resulting from channel lateral migration and associated cut and fill processes. The apparent paradox of unfilled accommodation space in the estuary is resolved by 1) winter wind–wave erosion of sand shoals to -3 m NAVD88 elevation and 2) asymmetric fluvial-tidal advection that results in net seaward transport of bed load in shallow tidal channels (> – 10 m NAVD88) and shallow subtidal shoals (> – 4 m NAVD88) during spring river flooding. 

Trends in Chesapeake Bay Sedimentation Rates during the Late Holocene

1990 ◽  
Vol 34 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Joseph F. Donoghue
Keyword(s):  
Sea Level Rise ◽  
Chesapeake Bay ◽  
Sea Level ◽  
Late Holocene ◽  
Tide Gauge ◽  
Past Century ◽  
Sedimentation Rates ◽  
Relative Sea Level ◽  
The Past ◽  
Relative Sea Level Rise

AbstractTrends are discernible in the estimates of late Holocene rates of sedimentation and sea-level rise for the Chesapeake Bay. During most of the Holocene Epoch sedimentation rates and relative sea-level rise were equal, within the limits of measurement, at approximately 1 mm yr−1. Sedimentation rates measured over the past century, however, are nearly an order of magnitude higher, while the rate of relative sea-level rise for the Chesapeake Bay now averages 3.3 mm yr−1, as measured on long-term tide gauge records. When the acceleration in these rates occurred is uncertain, but it appears to have been confined to the past millennium, and probably to the past few centuries. The rapid sedimentation rates recorded during historic time may be a temporary disequilibrium that has resulted from a recent acceleration in the rate of relative sea-level rise.

Contrasting facies patterns between river-dominated and symmetrical wave-dominated delta deposits

2021 ◽  
Vol 91 (3) ◽  
pp. 262-295
Author(s):  
BRIAN J. WILLIS ◽  
TAO SUN ◽  
R. BRUCE AINSWORTH
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Preferential Flow ◽  
Return Flow ◽  
Lateral Migration ◽  
Littoral Drift ◽  
Delta Front ◽  
Reference Case ◽  
Depositional Processes ◽  
The Impact

Abstract Process-physics-based, coupled hydrodynamic–morphodynamic delta models are constructed to understand preserved facies heterogeneities that can influence subsurface fluid flow. Two deltaic systems are compared that differ only in the presence of waves: one river dominated and the other strongly influenced by longshore currents. To understand an entire preserved deltaic succession, the growth of multiple laterally adjacent delta lobes is modeled to define delta axial to marginal facies trends through an entire regressive–transgressive depositional succession. The goal is to refine a facies model for symmetrical wave-dominated deltas (where littoral drift diverges from the delta lobe apex). Because many factors change depositional processes on deltas, the description of the river-dominated example is included to provide a direct reference case from which to define the impact of waves on preserved facies patterns. Both systems display strong facies trends from delta axis to margin that continued into inter-deltaic areas. River-dominated delta regression preserved a dendritic branching of compensationally stacked bodies. Transgression, initiated by sea-level rise, backfilled the main channel and deposited levees and splays on the submerging delta top. Wave-dominated deltas developed dual clinoforms: a shoreface clinoform built as littoral drift carried sediment away from the river month and onshore, and a subaqueous delta-front clinoform composed of sediment accumulated below wave base. Although littoral drift in both directions away from the delta axis stabilized the position of the river at the shoreline, distributary-channel avulsions and lateral migration of river flows across the subaqueous delta top produced heterogeneities in both sets of clinoform deposits. Separation of shoreface and subaqueous delta-front clinoforms across a subaqueous delta top eroded to wave base produced a discontinuity in progradational vertical successions that appeared gradual in some locations but abrupt in others. Littoral drift flows away from adjacent deltas converged in inter-deltaic areas, producing shallow water longshore bars cut by wave-return-flow channels with associated terminal mouth bars. Transgression initiated by sea-level rise initially led to vertical aggradation of wave-reworked sheet sands on the subaqueous delta top and then retreating shoreface barrier sands as the subaerial delta top flooded. Pseudo inter-well flow tests responded to local heterogeneities in the preserved deposits. As expected, abandoned channels in the river-dominated case defined shoreline-perpendicular preferential flow paths and wave-dominated delta deposits are more locally homogeneous, but scenarios for development of more pronounced shore-parallel heterogeneity patterns for wave-influenced deltas are discussed. The results highlight the need to consider the dual clinoform nature of wave-dominated delta deposition for facies prediction and subsurface interpretation.

scholarly journals Late Holocene sea-level change around Newfoundland

2007 ◽  
Vol 44 (10) ◽  
pp. 1453-1465 ◽  
Author(s):  
Julia F Daly ◽  
Daniel F Belknap ◽  
Joseph T Kelley ◽  
Trevor Bell
Keyword(s):  
Salt Marsh ◽  
Sea Level Rise ◽  
Sea Level ◽  
Late Holocene ◽  
Sea Level Change ◽  
Laurentide Ice Sheet ◽  
Change Analysis ◽  
Level Change ◽  
Rising Sea Level ◽  
Holocene Sea Level

Differential sea-level change in formerly glaciated areas is predicted owing to variability in extent and timing of glacial coverage. Newfoundland is situated close to the margin of the former Laurentide ice sheet, and the orientation of the shoreline affords the opportunity to investigate variable rates and magnitudes of sea-level change. Analysis of salt-marsh records at four sites around the island yields late Holocene sea-level trends. These trends indicate differential sea-level change in recent millennia. A north–south geographic trend reflects submergence in the south, very slow sea-level rise in the northeast, and a recent transition from falling to rising sea-level at the base of the Northern Peninsula. This variability is best explained as a continued isostatic response to deglaciation.

scholarly journals Rapid inundation of southern Florida coastline despite low relative sea-level rise rates during the late-Holocene

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Miriam C. Jones ◽  
G. Lynn Wingard ◽  
Bethany Stackhouse ◽  
Katherine Keller ◽  
Debra Willard ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Late Holocene ◽  
Relative Sea Level ◽  
Relative Sea Level Rise ◽  
Southern Florida

Late-Holocene evolution of a coastal lagoon in the Gulf of Lions (South of France)

2010 ◽  
Vol 181 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Pierre Sabatier ◽  
Laurent Dezileau ◽  
Mickaël Barbier ◽  
Olivier Raynal ◽  
Johanna Lofi ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Lagoon ◽  
Late Holocene ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Coastal System ◽  
Gulf Of Lions ◽  
Marine Sand ◽  
Radiocarbon Data

Abstract The central part of the Gulf of Lions shoreline is characterized by many coastal wetlands that resulted from the interaction between a process of shoreline regularization by migrations of littoral barriers and a slow filling of the back-barrier areas by the riverine and marine inputs. Analyses of Late-Holocene deposits with a very high-resolution multi-proxy study of two sediment cores, allow us to reconstruct the evolution of this coastal system. Two main Holocene sediment units are identified overlying a Pliocene carbonate continental formation. The lower unit consists of sandy and pebbly marine sediments deposited around 7800 B.P., during the final stand of the last sea level rise. Just above, the upper unit displays lagoonal grey clay silts with shells and some intercalated layers of silty sands related to paleostorm events. The age model was established from radiocarbon dating, for the oldest part of the core. Over the last century, sedimentation rates were calculated using the CFCS 210Pb model, together with 137Cs data. Radiocarbon data show an increase in the accumulation rate from the base to the top of cores. Marine sand units related to the last transgressive deposit allow to refine the curve of Holocene post-glacial sea level rise. Sedimentological and faunal analyses associated with chronological data provide a means for reconstructing the Late-Holocene paleoenvironments along this part of the coast and suggest that the final closure of the coastal lagoon by the sandy barrier occurred at around 730 ± 120 yr cal B.P. The beginning of this closure, together with the progradation of the coastal plain, could be responsible for the decline in economic activity of the Lattara harbour during the Roman period.

scholarly journals Spatial variability of late Holocene and 20th century sea-level rise along the Atlantic coast of the United States

Geology ◽  
2009 ◽  
Vol 37 (12) ◽  
pp. 1115-1118 ◽  
Author(s):  
S. E. Engelhart ◽  
B. P. Horton ◽  
B. C. Douglas ◽  
W. R. Peltier ◽  
T. E. Tornqvist
Keyword(s):  
United States ◽  
Spatial Variability ◽  
Sea Level Rise ◽  
Sea Level ◽  
20Th Century ◽  
Late Holocene ◽  
Atlantic Coast ◽  
The United States

Factors Controlling Tidal Flat Response to Sea Level Rise: Roberts Bank, British Columbia, Canada

2006 ◽  
Author(s):  
Alexandra Shaw ◽  
D. Gwyn Lintern ◽  
Philip R. Hill ◽  
Chris Houser
Keyword(s):  
British Columbia ◽  
Sea Level Rise ◽  
Sea Level ◽  
Tidal Flat

scholarly journals New data from terp excavations on sea-level index points and salt marsh sedimentation rates in the eastern part of the Dutch Wadden Sea

2018 ◽  
Vol 97 (1-2) ◽  
pp. 31-43 ◽  
Author(s):  
Annet Nieuwhof ◽  
Peter C. Vos
Keyword(s):  
Salt Marsh ◽  
Sea Level ◽  
Tidal Flat ◽  
Wadden Sea ◽  
High Water ◽  
Sedimentation Rates ◽  
Similar Data ◽  
Geological Data ◽  
Rate Of Development ◽  
Upper Limit

AbstractThis paper presents new geological data from two terp excavations at Englum and Ezinge, in the Dutch province of Groningen, and compares them to similar data from the western part of Friesland, in particular from the terp of Wijnaldum-Tjitsma. This terp is situated at a salt marsh ridge of the same height and thickness as Englum and Ezinge, although habitation started 650 years later at Wijnaldum. The measured levels of the tidal-flat/salt-marsh boundary underneath these terps make it possible to reconstruct palaeo-Mean High Water (MHW) levels. These sea-level index points show that palaeo-MHW in the Groningen part of the Wadden Sea was at the upper limit of the range of palaeo-MHW that has been reconstructed for the Dutch Wadden Sea on the basis of data from its western part. The deviating levels indicate that there are differences between regions of the Wadden Sea; this has earlier been established for the German section of the Wadden Sea. In the eastern part of the Dutch Wadden Sea, MHW nowadays is considerably higher than in the western part of the Wadden Sea; the data suggest that this may have been the case already in the 1st millennium BC. Salt marsh levels under dated terp layers make it possible to establish the rate of sedimentation of the developing salt marsh, at 23–91 cm per century for the pioneer zone and low marsh. This rate of development slowed to 4–5 cm per century for the middle marsh and 3–4 cm per century for the high salt marsh.

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