Longshore Drift and Depositional Landforms
Compiled by Mark Francek (more info) at Carleton College (SERC) and Central Michigan University
Find animations and images showing a variety of depositional landforms resulting from longshore drift. There are also animations that detail what happens when humans interrupt sediment transport through river and coastal engineering projects.
Longshore and Beach Drift, Prentice Hall: This Flash animation presents beach drift and longshore current motion based on the oblique approach of waves. These processes are highlighted through simple moving arrows.
Seasonal Beach Deposition Patterns, McGraw Hill: A relatively simple Flash animation contrasting sediment transport during winter and summer. The summer is characterized by lower energy, longer wavelengths, and sediment accumulating on the beach face. In contrast, the storms of winter create higher energy waves, shorter wavelengths, and sediment deposited as bars offshore. Access the animation by clicking on the "Seasonal Cycle of a Beach" link.
Baymouth Bar Formation, McGraw Hill: This Flash animation recounts how a spit, caused by longshore drift, eventually seals off an embayment, forming a baymouth bar. Access the animation by clicking on the "Spits and Baymouth Bars" link.
Spit Formation, Wycombe (more info) : This two step Flash animated slide show illustrates how a spit forms under the influence of longshore drift. As the longshore current passes a headland, it slows, and entrained sediment is deposited in a line down current of the headland.
Land Loss Animations, USGS (more info) : Find a movie in the Real Media format depicting significant wetland lost along the Louisiana coast due to leveeing and other modifications of the Mississippi and Atchafalaya rivers. Unlike many of the animations present in this section, the spatial patterns depicted here result from sediment starvation. "The river delivered 463 million tons of sediment a year between 1930 and 1952, but beginning in 1963, the sediment load dropped to 141 million tons. The decrease most likely occurred because of erosion control along the river's banks and dam and reservoir construction on its tributaries." From Why is the land in south Louisiana disappearing? (more info) . The animation would be more visually effective in appreciating the scope of the wetland lost if the color of disappearing wetlands was blue rather than a shade of red. The home site for these animations, "LA Coast" has a wealth of information on wetland depletion, development issues, slide shows, photos, 360 degree virtual reality video clips, and a kid's corner
American Coastlines, NOAA (more info) : Find hundreds of searchable coastal images from Alaska, Hawaii, Cheasapeake Bay, the Southeast, and historical images rendering of what coastlines looked like to early explorers. Images with very brief annotations are available in low and high resolution versions.
