This study examines the Holocene stratigraphic record and paleoenvironmental evolution of a large estuarine system, at high temporal and spatial resolution, in the context of changing climate, sea level, and hydrodynamics. New data are used to examine two time periods of increased marine influence within Pamlico Sound in northeastern North Carolina interpreted to be the result of extensive barrier island segmentation synchronous with periods of rapid climate change during the late Holocene. The study reveals the controls on the stratigraphic development and the highly dynamic character of the coastal system in response to climate, and sea-level change as it interacts with paleotopography. These findings can be used to inform projections of future environmental changes. Estuarine waters occupied paleovalleys in the Pamlico Sound region as early as ca. 7500 cal BP and Pleistocene interfluves separated the paleovalleys from the Atlantic Ocean until ca. 5500 cal BP, when they were flooded by rising sea-level forming the broad, shallow Pamlico Sound. Initial barrier islands and shoals likely formed sometime between 5500 and 5000 cal BP, providing the geomorphic setting for continued estuarine conditions behind the barriers. At ca. 4000 cal BP, an increase in marine influence and sand content is detected in multiple cores, and is correlated to seismic data within the northern Pamlico Sound basin. This change is interpreted to be the result of increased segmentation of barrier islands (thus a greater number of inlets, or wider inlets), which is consistent with a rapid transgression seen in other areas of the U.S. east coast. The segmentation may have been partially facilitated by a rapid increase in lagoonal area and tidal prism by overtopping of interfluves. Greater barrier island continuity is evident from 3500 to 1200 cal BP, as indicated by muddy deposits with low brackish estuarine foraminiferal assemblages. At ca. 1200 cal BP, seismic, sedimentological and micropaleontological data suggest an increase in wave and current energy and marine influence throughout southeastern 3 Pamlico Sound. These changes are interpreted to represent extensive segmentation of the barrier islands during the Medieval Climate Anomaly (MCA). Since ca. cal BP, the Pamlico Sound system has returned to a more restricted state, as inlets have closed. Currently only three major inlets segment the Outer Banks, the barrier island system fronting Pamlico Sound, but warming climate and increasing rates of sea-level rise suggest another episode of barrier island segmentation began about a half century ago and appears that it may extend into the near future.
The deglaciation record of the Ontario Lowland and Mohawk Valley of North America is important for constraining the retreat history of the Laurentide Ice Sheet, end-Pleistocene paleoclimate, and ice-sheet processes. The Mohawk Valley was an important meltwater drainage route during the last deglaciation, with the area around modern Oneida Lake acting as a valve for meltwater discharge into the North Atlantic Ocean. The Mohawk Valley was occupied by the Oneida Lobe and Oneida Ice Stream during the last deglacial period. Multichannel seismic reflection data can be used to generate images of preglacial surfaces and internal structures of glacial bedforms and proglacial lake deposits, thus contributing to studies of deglaciation. This paper uses 217 km of offshore multichannel seismic reflection data to image the entire Quaternary section of the Oneida basin. A proglacial lake and paleo-calving margin is interpreted, which likely accelerated the Oneida Ice Stream, resulting in elongated bedforms observed west of the lake. The glacial bedforms identified in this study are buried by proglacial lake deposits, indicating the Oneida basin contains a record of glacial meltwater processes, including a 60-m-thick proglacial interval in eastern Oneida Lake.
Sedimentologic and topographic data from Hurricane Sandy washover deposits were collected from southern Long Beach Island, New Jersey, in order to document changes to the barrier-island beaches, dunes, and coastal wetlands caused by Hurricane Sandy and subsequent storm events. These data will provide a baseline dataset for use in future coastal change descriptive and predictive studies and assessments. The data presented here were collected as part of the U.S. Geological Survey's Barrier Island and Estuarine Wetland Physical Change Assessment Project (http://coastal.er.usgs.gov/sandy-wetland-assessment/), which aims to assess ecological and societal vulnerability that results from long-and short-term physical changes to barrier islands and coastal wetlands. This report describes data that were collected in April 2015, approximately 2½ years after Hurricane Sandy's landfall on October 29, 2012. During the field campaign, washover deposits were photographed and described, and sediment cores, sediment samples, and surface-elevation data were collected. Data collected during this study, including sample locations and elevations, core photographs, computed tomography scans, descriptive core logs, sediment grain-size data, and accompanying Federal Geographic Data Committee metadata, are available in the associated U.S. Geological Survey data release (Bishop and others, 2016; http://dx.doi.org/10.5066/F7PK0D7S).
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