Coastal Processes

1
Coastal Processes
http//pipingplover.fws.gov/images/sign_lg.jpg
2
Continental Margins
Active - has an active plate bounday subduction
or transform faulting narrow shelf with cliffs
http//pubs.usgs.gov/of/2004/1007/images/geologict
ime.gif
Passive - far removed from plate boundary broad
shelf with extensive beaches
At the different margins, you have different
features and behaviors
3
Daily Tides
Remember F
G m1 m2
R2
The material closer to the Moon gets pulled
toward it with greater force than material that
is further away. This squeezes the material,
creating an object that is longer in
onedirection than the other
4
Neap and Spring Tides
When the Sun and Moon align, the tidal effect
from both add to create a stronger tide
http//www.nos.noaa.gov/education/tides/media/tide
06a_450.gif
When the Sun and Moonform a 90 degree angle
withrespect to the Earth, their tidal effects
subtract, creatinga weaker tide
5
Sea Level Changes

• Ocean levels on a coast can change for a number
  of reasons
• Isostasy - land rebound after Ice Age sediment
  loading depresses
• Tectonic shift - plate movement causes motion up
  or down
• Glacial melting - more water in the ocean means
  an levels go up
• Ocean warming - water expands as warmed
• Land warming - rock expands when warmer depends
  on where located
• De-watering of sediment - land slumping as water
  moves out

6
Mississippi River - Example
http//www.lacoast.gov/geography/index.htm
7
Barrier Islands
Bertha - 7/16/96            Fran -9/7/96  
     Bonnie - 8/28/98
Long, narrow islands that form parallel to
coasts provideprotection to coast against
strong storms very susceptible to disturbance
by storms, but also by mankinds intervention to
keep them stable
8
Estuaries
Partially enclosed body of water formed where
freshwater rivers flow into the salty ocean,
creating a brackish environment Very susceptible
to changes in flow of freshwater or salt
water Important ecosystem for many forms of
wildlife
http//gulfsci.usgs.gov/maps/sat/satmap.html