In subtidal environments, processes of sediment transport are widely influenced by three factors: initiation of motion (erosion), transport, and deposition. Sediment Transport and Deposition in Subtidal Environments Subtidal environments are important in understanding depositional environments as they are areas where facies are more likely to be preserved. Typically tidal flats are broken into three different sections, which may be abundant or absent in each individual tidal flat: Supratidal, Intertidal, and subtidal (4). Subtidal environments have a wide distribution of facies associated with water depth and tidal and wave energy. Tidal flats or mudflats form where tides alternately flood and expose low areas along the coast (4). Tides are susceptible to change in sea levels. High tide is when water advances to its furthest extent and low tides is when it recedes to its furthest extent. Tides are driven by a combination of gravity fields of the sun and moon in addition to the Coriolis effect. The alternating advance and retreat of seawater along the coast, rivers and lakes are called tides. Shallow water waves occur when the depth is less than 1/20 of a wavelength(1). In shallow waves, the wave base connects with the sea floor changing their motion from orbital to horizontal (1). As the wave moves, water moves forward and up over wave crests and down into the troughs (1). Water move as a reaction to this energy in orbital motions creating the physical components of a wave as seen in Figure 1 (1). Waves are a form of energy that is being transmitted. Interactive factors that influence subtidal environments are tides, waves, and ocean currents. Tides, waves and currents play an important role in shaping and influencing the creation of subtidal environments of our modern coastal beaches, estuaries and lagoons. \)įigure 1: Components of a Wave (Modified by PW from Steven Earle “Physical Geology”.)
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