florida's barrier islands
TRANSCRIPT
BARRIER ISLAND FORMATION
1. Offshore bar theory
2. Spit accretion theory
3. Submergence theory
(http://coast.noaa.gov/archived/beachnourishment/html/geo/barrier.htm?redirect=301ocm)
(http://upload.wikimedia.org/wikipedia/commons/thumb/4/48/Accreting_coast_Image6.svg/360px-Accreting_coast_Image6.svg.png)
http://faculty.scf.edu/rizkf/OCE1001/Images/estuarytypes.jpg
(a) Coastal plain: Chesapeake Bay- drowned river valley
(b) Fjord: Puget Sound- glaciers
(c) Bar-built: IRL Barrier Islands
(d) Tectonic: San Francisco Bay- San Andreas faulthttp://en.wikipedia.org/wiki/Estuary
CHANGING COASTLINES
Coastline changes with sea level
and global temperatures
http://www.fnai.org/ARROW/almanac/geology/geology_history.cfm
CAUSES OF EARTH’S TEMPERATURE FLUCTUATIONS
• Moving continents affect oceanic and atmospheric circulation
• CO2 concentrations (high CO2 => high temp)• Volcanic eruptions, extraterrestrial collisions
(dust reflects sunlight => low temp)• Milankovitch cycles
• Eccentricity• How elliptical the orbit is
• Axial tilt (obliquity)• Diff btw orbital and rotational axis
• Precession- axis wobbles like a spinning top• 26,000 year cycle
• Seasons- small scale• Relates to tilt and not distance from
sunhttp://en.wikipedia.org/wiki/Milankovitch_cycles
http://en.wikipedia.org/wiki/Milankovitch_cycles
Circular orbit, no eccentricity
Orbit with 0.5 eccentricity.
http://www.johnenglander.net/sea-level-rise-blog/why-sea-level-will-rise-centuries-ultimately-100-feet
TECTONIC PLATE MOVEMENT AND
FORMATION OF FLORIDA• Plates can move up to 10cm/yr!• Driven by convection currents deep
underground that either create or destroy Earth’s crust
http://en.wikipedia.org/wiki/Plate_tectonicshttp://www.ucmp.berkeley.edu/education/dynamic/session1/sess1_earthcurrents.html
TECTONIC PLATE MOVEMENT AND
FORMATION OF FLORIDA
• Mid Atlantic Ridge created Atlantic ocean• Was a factor in the separation of Pangea
• Crust being created, pushed land apart, gave east coast N. America sloping beaches, while the west coast slides over another plate, creating cliffed beaches
http://www.amnh.org/education/resources/rfl/web/bulletins/earth/A/6/4/A_0007_04_00_w_image1_lg.jpg
HOW OLD ARE FLORIDA’S BARRIER ISLANDS?
• About 18,000 years young• End of the Pleistocene • Last glacial melting period • Susceptible to frequent changes• Human and environment influenced
http://fcit.usf.edu/florida/teacher/science/mod2/resources/changing.coastlines.pdf
http://tracks.roojoom.com/u/shirly-ronen-harel,60/the-geological-time-scale-explained,3979
GEOLOGIC TIME SCALE