Section 4

Erosional ProblemsAmerica's Pacific CoastNarrow beaches with steep cliffs and mountain rangesProblems come from the changing of natural systems by humans.Big Problem: Beaches are becoming more narrow.Sand supplied by rivers.Dams stop the sand from coming to the beaches.Sand protects cliffs from waves.Without the extra sand, cliffs are experiencing quicker erosion.Erosion changes by year depending on storms.If the sea levels rise, more shoreline erosion is to occur.Shoreline Erosion

Shoreline Erosion

Atlantic CoastAtlantic Coast Pacific Coast

Classification based upon sea level changesTwo types of coastsEmergent coasts - develop because of of area uplift or a drop of sea level Exhibit specific landformsWave-cut cliffs - erosion causes cliffs to crumble and retreatMarine terrace - Wave-cut platform that is uplifted above sea level by tectonic forces and exhibits a seaward-sloping shapeShoreline Types

Classification based upon sea level changesTwo types of coastsSubmergent coasts - created when sea level rises or the land adjacent to the sea subsidesExhibit estuariesEstuaries - drowned river mouthsShoreline Types

Tide- Daily change in the elevation of the ocean surfaceThe easiest ocean movements to observe other than wavesCaused by the gravitational attraction exerted upon Earth by the Moon and, to a lesser extent, by the SunTidal bulge- the Moon's gravitational force causes water to bulge on the sides of Earth nearest and directly opposite to the Moon The tidal bulges remain in place while Earth rotates "through" them and causes high and low tidesMost places on Earth experience two high tides and two low tides each day Tides

Spring tide- highest tidal range that occurs near the times of the new and full moons, when the Sun, Earth, and Moon are alignedNeap tide- lowest tidal range, occurring near the times of the first- and third-quarter phases of the moonEvery month, there are two spring tides and two neap tides, each about one week apart

Tides

There are three types of tidal patterns*Diurnal Tidal Pattern-Characterized by Single high tide and single low tide each tidal day.Ex. Northern Shore of Gulf of Mexico*Semidiurnal Tidal Pattern-Characterized by Two high tides at the same height and two low tides at the same height each tidal day.Ex. Along the Atlantic Coast of the United States of America

Tidal Patterns

*Mixed Tidal Pattern-Characterized by Two high tides and two low tides each tidal day. Unlike semidiurnal mixed tidal patterns the heights of the high tides differ greatly as well as the low tides.Ex. The Pacific coast of the United States of AmericaSemidiurnalMixedDiurnal

Tidal currenthorizontal flow of water accompanying the rise and fall of tidesinduced by tidal forcescurrents advancing into coastal zones make flood currentscurrents moving out to sea make ebb currents Tidal flatsAreas affected by slack water (alternating ebb and flood currents)tidal flats vary from long, narrow stips seaward of the beach to zones extending for several km, depending on their nature.

Tidal deltaDeposit of sediments due to tidal currentsMay develop inland of an inlet as a flood delta or seaward of an inlet as an ebb deltaflood deltas are more common and more prominent that ebb deltas.

"Coastal Hypoxia Research Program (CHRP 2005): Watershed-Estuary-Species Nutrient Susceptibility." : NaturalResources and Environment : University of Michigan. Web. 24 May 2013."FOSTER-LIS - Estuarine Physical Oceanography." FOSTER-LIS - Estuarine Physical Oceanography. Graduate School of Oceanography, Web. 24 May 2013.

"Freshwater-Saltwater Interactions along the Atlantic Coast." USGS Ground-Water Resources Program (GWRP): Web. 24 May 2013. .National Oceanic and Atmospheric Administration. "Tidal Hydrology, Hydraulics, and Scour at Bridges Hydraulic EngineeringCircular No. 25 Appendix B - Hydraulics Engineering - FHWA." Tidal Hydrology, Hydraulics, and Scour at BridgesHydraulic Engineering Circular No. 25 Appendix B - Hydraulics Engineering - FHWA. Federal Highway Administration, 4 July 2011. Web. 24 May 2013.

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