Chapter 15 Section 2 By Suzanne Black, Nick Stratton, Jordan Henault, Emily O'Donnell, Bryan Perlak, Shayne McConnell

Shoreline- line that marks the contact between land and sea o Migrates because of changing tides o Gradually shifts because of changing sea level o Shore- area that extends between the lowest tide level and the highest  Changes because of storm waves Coastline- marks the coast's seaward edge o Inland boundary isn't easy to determine o It's divided into the foreshore and backshore  Foreshore- the area exposed when the tide is out.... Submerged when the tide is in  Backshore- landward of the high- tide shoreline.... Only affected by waves during storms.... Very dry o Two other common zones:  Nearshore zone- lies between the low- tide shoreline and the line where waves break at low- tide  Offshore zone- seaward of nearshore zone Composition of Beaches

Beach- accumulation of sediment found along the landward margin of the ocean or a lake o May extend for tens or hundreds of kilometers o Irregular coasts call for beach formation to be confined to a small area  i.e. bay or gulf o Beaches consist of one or more berms- relatively flat platforms often composed of sand that are adjacent to coastal dunes or cliffs and marked by a change in slope at the seaward edge o Beach face- the wet sloping surface that extends from the berm to the shore- line  Berms are the soft, hot part of the beach, while the beach face is the hard- packed, wet sand near the ocean. Composed of whatever materials are locally abundant o Many beaches dominated by quartz, however minerals that dominate the surrounding areas usually dominate the beaches Composition of Beaches Continued

Beaches in Florida dominated by shells and other dead organisms o Visual composition of a beach: Composition of Beaches Continued

The tops of waves are the crests, which are separated by troughs. Halfway between the crests and troughs is the still water level. o The vertical distance between trough and crest is called the Wave height. o The distance between successive crests (or troughs) is the wavelength. o The time it takes one full wave- one wavelength- to pass a fixed position is the wave period. Wave Characteristics

The height, length, and period that are eventually achieved by a wave depend on three factors. o Wind Speed o Length of time the wind has blown o Fetch, the distance that the wind has traveled across open water As the quantity of energy transferred from the wind to the water increases, both the height, and the steepness of the waves increases. Eventually, a critical point is reached where waves grow so tall they topple over, forming ocean breakers called whitecaps. Wave Characteristics Cont.

When the wind stops or changes direction, waves continue on without relation to local winds. The waves also go under a gradual change to swells, which are waves lower in height and longer in length and may carry a storm's energy to distant shores. Wave Characteristics Cont.

water particles move in a circular motion water particle movement occurs below a depth equal to one half the wavelength wave particles motion decreases with depth wave particles are largest at the crest then decrease until the half of the wave height they rotate with the motion of the wavelength Motions of Water Particles in a Wave

Abrasion o the sawing and grinding action of water containing rock fragments Beaches(rivers of sand) Wave Refraction o Refringere = to break up o Bending of waves o Affects distribution of energy along the shore. =" Wave Erosion and Refraction

Beach Drift o The drifting of sediments, especially marine sediments, in patterns parallel to the contours of a beach, due to the action of the action of waves and currents. Longshore Currents o When waves strike the shore at an angle it creates a strong current parallel to the shore that, in turn, causes beach drift.  Sand spit As longshore currents and beach drift work together, the moved sediment creates an outcrop of sand going out in the direction of the longshore currrent. Pop a molly I'm sweat!  Beach Drift and Longshore Currents

Longshore Currents  The longshore current often moves in the same direction as the prevailing coastal wind. Beach Drift and Longshore Currents