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Coastal Morphology

GPR profile
Subsurface image of paleo-shorelines beneath a coastal plain in southern Brazil (ocean is to the right). Enlarge »
paleosol lithuania
Paleosol exposed in a relict dune along northern Curonian Spit, Lithuania. Enlarge »
storm scarp
Recent storm scarp and GPR image of a relict scarp (arrow), southern Brazil. Enlarge »
inlet
Hog Inlet, a small tidal inlet in South Carolina with active development on its southern barrier. Enlarge »

Positioned at the land-ocean interface, coastal sedimentary systems provide ideal archives for reconstructing the effects of climate, sea level, and sediment supply on time scales from years to millennia. Using a combination of high-resolution geophysical (ground-penetrating radar [GPR]) imaging and sediment cores, it is possible to reconstruct the various phases in the construction of narrow barriers or wide coastal plains. Areas of active research include the U.S. Atlantic Coast, river-associated strandplains of southern Brazil, and small islands in the northern Persian Gulf.

Coastal Dune Research
Coastal sand dunes are common landforms along continental margins. Prior and in addition to recent human-induced changes, the origin, migration, and stabilization of dunes has been intimately linked to sediment availability, sea level change, and climatic factors (precipitation, temperature, prevailing winds). Through integrated geophysical, sedimentological, and geochronological approach, our research aims to reconstruct the long-term evolution of coastal dunefields. Current projects focus on Holocene dunes in New England and along the Baltic Sea coast.

Storm Signatures in Barrier Sequences
In many parts of the world, sedimentary records of storm- and tsunami-induced shoreline erosion, retreat, and flooding are preserved within sediment-rich prograded coastal plain sequences, although their geological signatures are often obscured by natural or human-induced changes. Among the most diagnostic features of erosion are steep berm and dune scarps, regional unconformities (discontinuities), layers of coarse sediment or shell hash, as well as extensive accumulations of heavy minerals. Geophysical records are used to identify and map relict erosional features, with chronology provided by radiocarbon and optical dating techniques. Magnetic susceptibility of various sand fractions will help to quantify the properties of lag deposits produced by high-energy wave and wind conditions.

Paleo-Inlet Research
Coastal barrier segments adjacent to active tidal inlets often undergo rapid and dramatic changes. Similarly, former inlets may play an important role in sediment dynamics, backbarrier ecology, tidal prism changes, and landscape re-organization for many years following channel closure. Because some inlets form during major storms, the vulnerability of coastal barriers to breaching and overwash, as well as their response to the opening of new inlets, are among the key factors to be considered by coastal managers and engineers. In recent years, geomorphic mapping and geophysical surveying at a number of sites documented the locations and dimensions of several historical inlets and revealed a number of previously unknown relict channels.

For more information please contact:

Ilya Buynevich (ibuynevich@whoi.edu)

 

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