6. Why do sea levels change globally???

10. Beaches are easily recognizable secondary coasts
Beaches are easily recognizable secondary coasts. Form from the deposition of eroded
sediment in “quiet” areas.

11. Movement of eroded sediment, as well as sand along an established beach,
is caused by 2 main features – longshore current and longshore drift.

13. Rip Currents are narrow, fast currents moving offshore and are produced
by the backwash from the longshore current
Can be dangerous to swimmers - swim across (parallel to shore) or
ride them out until they slow just offshore
MSCI 210 – Chapter 9 – Coasts, Estuaries, and Environmental Issues

17. Barrier Islands
Long, offshore deposits of land which are parallel to the coast
Often provide a barrier to storm waves
Origin is complex - many were formed during the rise in sea level
sea level following the last ice age (18,000 years ago)
Nearly continuous along the
US Atlantic coast and Gulf of Mexico

18. Beach Profile Animation
Tobay Beach at Jones Beach Island, NY

22. Fringing Reef
Figure 11.23
A small section of the Great Barrier Reef, Queensland, Australia. This coast has been extensively modified by biological activity.

23. Estuaries Tectonic Coastal Plain Fjord Bar-built
Estuary - a partially enclosed body of coastal water where salty ocean
water is mixed by water from land runoff and, typically, rivers.
Are usually associated with river mouths
May support important commercial and recreational fisheries
Many major seaports are estuaries - lots of ship traffic
Origin of Estuaries
Most were created by sea level rise over the past 18,000 years (since
the last ice age)
During this time, sea level has risen about 180 meters (400 feet)
Four Major Classes of Estuaries
Tectonic
San Francisco Bay
Coastal Plain
Chesapeake Bay
Galveston Bay
Fjord
Strait of Juan de Fuca
Washington
Bar-built
Laguna Madre,
Texas

24. =coastal plain

25. Estuarine Circulation
In areas where river input exceeds evaporation, freshwater water
flows out of the estuary at the surface
Saltier water flows into the estuary along the bottom
Mixing patterns vary with season, tides, freshwater inflow, and wind
Residual flow – currents not associated with tidal ebb and flood

26. Estuaries
Are vital natural ecosystems - health is essential for world’s fisheries
Commercial and Recreational Importance
Human activities have had a major impact on estuaries
Waste inputs, habitat destruction, chemical pollution, and declines in overall water quality peaked in the 1970’s
The Clean Water Act and improvements in waste treatment are big steps toward cleaning up estuaries
Population will continue to increase in the coastal zone and estuaries will experience increasing use
Eutrophication is a general term that describes an overall decline in water quality due to increased inputs of nutrients – including animal waste and fertilizers.
Many estuaries in the US are under increasing stress imposed by human activities in the coastal zone. Habitat destruction is major cause of concern but the increased sources of pollutants that come along with increased development are also major stressors.
Concept of Sustainable Coastal Development
Inputs can come from Point or Non-Point Sources
Non-point sources are the most difficult to control and will be
the major problem over the next few decades

27. Coastal Development
National Flood Insurance Program
For $1000, you can purchase a $200,000 insurance policy
to protect against flood damage
Policy would cost $18,000 if purchased from private insurance company
Affordable insurance encouraged overdevelopment of the coastal zone
1982 Coastal Barrier Rezoning Act
Excludes new construction in undeveloped coastal areas from
federal insurance assistance
Miami Beach
Undeveloped salt marshes were critical in protecting many areas during Katrina.