If the setting is not tropical, or is dominated by fine sediment input from land, then the environment will be dominated by sediments derived from land sources, or siliciclastic sediment. The subtidal environments may be dominated by calcareous sediments (calcium carbonate) if the water is warm and clear enough (Wilson, 1975). The marine environments seaward of the foreshore (below the low tide line) can collectively be referred to as the subtidal environment (literally, below the tides). The seaward extent of the shoreface may be found within a few hundred yards or many miles of the shoreline, depending on the steepness of the seafloor.įor the purposes of this chapter, marine features and processes will be considered seaward from the low tide line-that is, beginning with the shoreface. The shoreface typically extends seaward to a water depth of 30 feet, though the depth is variable depending on the local wave heights. Because the beach is actually defined by the movement of sand, the shoreface, then, is the seaward extent of the beach. Another way to look at it is that the shoreface is the seaward extent of sediment movement caused by waves. The shoreface is the zone where waves approaching land first start to interact with the seafloor. Seaward of the foreshore is the inshore, commonly called the shoreface, the deeper water extent of the beach system. Looking seaward, the shallowest part of the beach is the intertidal zone, the portion between high tide and low tide. This is known as the backshore, but is also often referred to as the dry beach, the recreational beach, or the subaerial beach. To define the limits of the beach and the limits of the nearshore marine system, begin with the above water part of the beach, the part landward of the shoreline. Standard beach terminology delineating the environmental zones of the nearshore system is shown in Figure 1. Part of the beach system also belongs to the nearshore zone, so it is impossible to completely disassociate the beach/ transitional zone from the nearshore marine system. Beach features and processes are covered in another chapter of this volume (Bush and Young, this volume). The transition zone between terrestrial and marine environments includes such environments as tidal flats, estuaries, dunes, and beaches and barrier islands. All environments can be considered as either terrestrial (on land), marine (under water), or transitional (transitional between land and water). Marine environments include anything seaward of the shoreline, the dividing line between land and water. For permission to copy, contact ©2009 The Geological Society of America. Department of Geosciences, University of West Georgia, 1601 Maple Street, Carrollton, Georgia 30118, USAīush, D.M., 2009, Marine features and processes in Young, R., and Norby, L., eds., Geological Monitoring: Boulder, Colorado, Geological Society of America, p.
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