Geoarchaeology of the Nehalem spit: Redistribution of beeswax galleon wreck debris by Cascadia earthquake and tsunami (∼A.D. 1700), Oregon, USA

Peterson, Curt D.; Williams, Scott S.; Cruikshank, Kenneth M.; Dubè, John R.

doi:10.1002/gea.20349

Cited by 11 publications

(9 citation statements)

References 19 publications

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“…The abrupt subsidence event (1.0-1.5 m of relative SLR in the study area) was widespread throughout the three subcells (Peterson et al, 2000). However, a corresponding catastrophic beach retreat scarp was only preserved at the northern end of the Tillamook subcell ( Figure 2), where ~150 m of interseismic beach width recovery occurred from interplate recoupling and regional tectonic uplift, after ~1750 (Peterson et al, 2010). No preserved catastrophic beach retreat scarps have been found by these authors from any other beaches in the three-subcells study area.…”

Section: Evidence Of Declining Beach Sand Reservesmentioning

confidence: 91%

“…Profile elevations were tied into predicted tide levels from mid-swash runups (±0.25 m error) measured during the time of predicted mean tide level (MTL±0.1 hour). Beach sand thickness was established at multiple backshore and mid-beach sites by 1) seismic refraction and trenching in the Cannon Beach subcell (Pettit, 1990; and 2) ground penetrating radar (GPR) and sand augering (Tillamook and Netarts subcells) (Doyle, 1996;Peterson et al, 2010). GPR was also used to test for coseismic beach retreat scarps in the Nehalem Bay, Tillamook Bay, and Netarts Bay sand spits (H. Jol and C. Peterson, unpublished data, 2001;Losey, 2003;Peterson et al, 2010).…”

Section: Methodsmentioning

confidence: 99%

“…Profiles of active-beaches have been reported for 1) the Cannon Beach subcell (n=5) (Peterson et al, 1994), 2) the Tillamook subcell (n=7) (Doyle, 1996;Peterson et al, 2010), and 3) the Netarts subcell (n=7) (Percy et al, 1998;Minor and Peterson, 2016). These profiles extend from the foot of the exposed sea cliff or seaward side of the most recently stabilized foredune (> 50% vegetation cover) to the beach face intersection with MLLW, usually coinciding with the beach toe.…”

Section: Subcell Beach Profilesmentioning

confidence: 99%

“…The Cannon Beach subcell profiles are redrawn from. The Tillamook subcell profiles are redrawn fromDoyle (1996), with the exception of Tillamook 5061530 (25 m distance intervals), which is fromPeterson et al (2010). The elevation datum (0 m) is the mean lower low water (MLLW) tidal elevation, which is about 0.5 m below the 0 m NAVD88 vertical datum in the study area.…”

mentioning

confidence: 99%

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Predicted Responses of Beaches, Bays, and Inner-Shelf Sand Supplies to Potential Sea Level Rise (0.5-1.0 m) in Three Small Littoral Subcells in the High-Wave-Energy Northern Oregon Coast, USA

Peterson¹,

Doyle²,

Rosenfeld³

et al. 2020

JGG

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Three small subcells (Nehalem, Tillamook, and Netarts) totaling ~55 km shoreline length in the high-wave energy northern Oregon coast are evaluated for potential beach sand loss from sea level rise (SLR) of 0.5–1.0 m during the next century. The predicted erosion is based on beach sand displacement from the narrow beaches (average ~120 m width) to increased submarine accommodation spaces in the innermost-shelf (to 30 m water depth) and in the subcell estuaries (Tillamook Bay, Netarts Bay, and Nehalem Bay), following predicted near-future SLR. Beach sand sources from local rivers, paleo-shelf deposits, and/or sea cliff retreat are discriminated by distinctive heavy-mineral tracers. Modern beach sands in the study area are derived from river sand (~75 %) and paleo-shelf sand (~25 %). The supplies of paleo-shelf sand to the beaches have largely diminished in late-Holocene time. The river-enriched beach sands have been transported offshore to the inner-shelf (0–50 m water depth) to fill increasing accommodation space in the inner-shelf during latest-Holocene conditions of relative SLR (1.0 m ka-1). To evaluate the beach sand response to future SLR, representative beach profiles (n=17) and intervening beach segment distances were compiled to yield beach sand volumes above mean lower low water (MLLW) or shallower wave-cut platforms ‘bedrock’. Across-shore cross-sectional areas, as averaged for each subcell, are as follows; Cannon Beach (304 m2), Tillamook (683 m2), and Netarts (227 m2). Littoral sand displacements to the adjacent innermost-shelf (to 30 m water depth) and the marine-dominated areas of the three estuaries are based on assumed vertical sand accretion rates of 1.0 m per century and a conservative value of 0.5 m per century. The filling of such submarine accommodation spaces will displace all active-beach sand reserves in all three subcells for either the 1.0 m or 0.5 m thickness accommodation space scenarios. Large beach sand deficits, primarily from the filling of offshore accommodation spaces, could cause further retreat of soft-shorelines, including barrier spit and beach plain/dune deposits, in the Tillamook subcell (150-280 m) and in the southern half of the Netarts subcell (370-770 m). The accommodation space approach used to predict beach sand volume loss from future SLR should have broad applicability in complex littoral systems worldwide.

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Section: Evidence Of Declining Beach Sand Reservesmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Subcell Beach Profilesmentioning

confidence: 99%

mentioning

confidence: 99%

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Predicted Responses of Beaches, Bays, and Inner-Shelf Sand Supplies to Potential Sea Level Rise (0.5-1.0 m) in Three Small Littoral Subcells in the High-Wave-Energy Northern Oregon Coast, USA

Peterson¹,

Doyle²,

Rosenfeld³

et al. 2020

JGG

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“…The artifacts were tentatively traced to a lost Spanish galleon, possibly the San Francisco Xavier lost in 1705 (Giesecke, 2007) but the mechanism for the distribution of artifacts across the bay spit could not be explained. After geological studies established that tsunami cobbles and boulders were draped across the surface of the sand spit the across spit distribution of artifacts were attributed to nearfield tsunami surges (Peterson et al, 2011) resulting from the last Cascadia megathrust rupture (M w ~9.0) in 1700 (Satake et al, 1996). A renewed search of Spanish documents showed that another galleon Santo Cristo de Burgos had been lost in 1693, thereby permitting overland transport of artifacts by the 1700 Cascadia tsunami surges (Williams et al, 2017).…”

Section: Beeswax Galleon Shipwreckmentioning

confidence: 99%

Cascadia Earthquake-Triggered Rockslide Burial of Beeswax Galleon Wreck Timbers in a Sea Cliff Wave-Cut Platform Site, North Smuggler Cove, Oregon, USA

Peterson¹,

Williams²,

Andes³

2023

JGG

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Shipwreck timbers (n=27) from the Spanish galleon Santo Cristo de Burgos, also known as the Beeswax Wreck (lost in 1693), are examined for origins of multiple, simultaneous rockslide burials that protected and preserved the timbers on an intertidal wave-cut platform in the small Smuggler Cove in the Northern Oregon coast. The rockslides (n=3–4) that buried the shipwreck timbers are compared to nearby historic rockslide analogs to better establish the mechanisms of boulder distributions on the wave-cut platform. Large boulders (n=20), generally ≥1.0 m intermediate diameter, in the North Smuggler Cove (NSC) timber burial site were measured for estimated mass (1–41 t) and alongshore distribution below small gullies that routed the boulders to the wave-cut platform from overlying short (~100 m distance) but steep hillslopes (40–60% gradient). The multiple independent rockslides in the NSC site, dated to ~300 years by the buried Beeswax Wreck timbers, showed catastrophic, simultaneous activation by a widespread trigger. Anomalous rainfall and/or storm wave attack are unlikely mechanisms for these rockslide activations due to 1) hillslope protections from extended-upslope surface water discharge and 2) sea cliff protection from direct storm wave impacts. The most likely widespread trigger for rockslide activation in the NSC site is seismic ground shaking from an earthquake in the Central Cascadia subduction zone. Modern storm wind velocities (>10 s-1 sustained velocity and 170–225° bearing) and storm surge generated rip currents (≥0.5 km offshore distance) indicate that Beeswax Wreck timbers could have been transported north (1–10 km) to Smuggler Cove, within several winter seasons after the breakup of the Santo Cristo de Burgos. The most likely seismic trigger that could have activated the multiple rockslides in the NSC site, shortly after the brief accumulation of shipwreck timbers on the narrow, intertidal wave-cut platform in Smuggler Cove, is the 1700 Cascadia great earthquake (Mw~9.0). Additional sea cliff rockslide sites (n=8) in the central Cascadia margin are suggested for further investigations of seismically activated slope failures by the 1700 Cascadia great earthquake.

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Making the Exotic Mundane: The Manila Galleon, the Flota, and Globalization

Skowronek

2021

SpringerBriefs in Archaeology

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Geoarchaeology of the Nehalem spit: Redistribution of beeswax galleon wreck debris by Cascadia earthquake and tsunami (∼A.D. 1700), Oregon, USA

Cited by 11 publications

References 19 publications

Predicted Responses of Beaches, Bays, and Inner-Shelf Sand Supplies to Potential Sea Level Rise (0.5-1.0 m) in Three Small Littoral Subcells in the High-Wave-Energy Northern Oregon Coast, USA

Predicted Responses of Beaches, Bays, and Inner-Shelf Sand Supplies to Potential Sea Level Rise (0.5-1.0 m) in Three Small Littoral Subcells in the High-Wave-Energy Northern Oregon Coast, USA

Cascadia Earthquake-Triggered Rockslide Burial of Beeswax Galleon Wreck Timbers in a Sea Cliff Wave-Cut Platform Site, North Smuggler Cove, Oregon, USA

Making the Exotic Mundane: The Manila Galleon, the Flota, and Globalization

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