How Tectonics Affects Barrier Islands
Barrier Islands are always found along passive plate margins. The affects of plate tectonics is never a direct on these island systems. Plate tectonics does however play an important role in sea level change; this in turn will affect the position of these islands as well as their migration patterns, and the placement of the sediment supply source. In the event of sea level rising the islands will become submerged and the sands and sediments found there are likely to be eroded away due to offshore currents. The rise will also affect the closeness of the supply source (will change the position of the river mouth) and may or may not affect the strength of these currents. This increase in sea level height will cause the system to migrate inland to be nearer the new shoreline,horeline, thus bringing the islands closer to sediment supply. This increase in height may also cause the mud and silt sediments that were being deposited in the lagoons to become intermixed with the island sands if the rise is not high and fast. The falling of sea level due to plate tectonics will have the reverse affects the islands will migrate out away from the new shorelinehoreline and the system will start to rebuild itself ate this new level. It is important to note that not only will plate tectonics affect these islands inadvertently but that these islands may also affect plate tectonics directly. The load of the sediment on the continental shelf through time may be even so that the plate can sink enough to possible break and allow the shelf or margin to begin subduction or even to cause the change in sea level itself.
Wednesday, April 03, 2013