Beach evolutionBeach evolution occurs at the shoreline where sea, lake or river water is eroding the land. Beaches exist where sand accumulated from centuries-old, recurrent processes that erode rocky and sedimentary material into sand deposits. River deltas deposit silt from upriver, accreting at the river's outlet to extend lake or ocean shorelines. Catastrophic events such as tsunamis, hurricanes, and storm surges accelerate beach erosion. Beach accretion and erosion Tsunamis, potentially enormous waves often caused by earthquakes, have great erosional and sediment-reworking potential.
Oyster reefThe term oyster reef refers to dense aggregations of oysters that form large colonial communities. Because oyster larvae need to settle on hard substrates, new oyster reefs may form on stone or other hard marine debris. Eventually the oyster reef will propagate by spat settling on the shells of older or nonliving oysters. The dense aggregations of oysters are often referred to as an oyster reef, oyster bed, oyster bank, oyster bottom, or oyster bar interchangeably. These terms are not well defined and often regionally restricted.
