Where is Where is Andros??Andros??
Mercator ProjectionMercator Projection
World OceanWorld Ocean
What is the inner core made of?What is the inner core made of?
Why?Why?Because it is very dense and pulled to center by gravity
IronIron
What is the upper mantle ?What is the upper mantle ?
Solid or Solid or Liquid?Liquid?
Which is the highest density?Which is the highest density?
Ocean crustOcean crustOr Or Continental Continental
CrustCrust
Process is called Plate TectonicsProcess is called Plate Tectonics
Proposed byProposed by– Alfred WagnerAlfred Wagner– 1880-19301880-1930
Less dense Less dense (lighter) (lighter) continental plates continental plates float on heavier float on heavier oceanic platesoceanic plates
What is the energy source that What is the energy source that moves the plates???moves the plates???
Convection Currents- heated material Convection Currents- heated material expands (becomes less dense) and is expands (becomes less dense) and is forced up by heavier (more dense) material.forced up by heavier (more dense) material.
““Blanket Effect” – Super continent, Blanket Effect” – Super continent, Pangea, insulated hot interior, causing Pangea, insulated hot interior, causing heat build up and convection currents.heat build up and convection currents.Plates are drug along by this movementPlates are drug along by this movement
Convection currents moving Convection currents moving plates and forming new land at plates and forming new land at
oceanic ridgesoceanic ridges
Cindy Ebinger –plate tectonics Cindy Ebinger –plate tectonics
Studies rift Studies rift zones.. Has zones.. Has done most done most of her work of her work in Ethiopia, in Ethiopia, East AfricaEast Africa
Rift photo by Ebinger in EthiopiaRift photo by Ebinger in Ethiopia
Plates move apart Plates move apart 8-12 cm/year 8-12 cm/year
Fingernails grow 6 Fingernails grow 6 cm/yearcm/year
Rift in IcelandRift in Iceland
Youngest rock at the center – oldest rock Youngest rock at the center – oldest rock farthest from the center (rift valleys)farthest from the center (rift valleys)
Facts that support continental driftFacts that support continental drift
1. Similar 1. Similar shaped shaped continentscontinents
2. Similar fossils across Atlantic2. Similar fossils across Atlantic
3. Magnetic Reversals3. Magnetic Reversals
4.4. Sediment deepest at edges of Sediment deepest at edges of continents – thinnest at ridge (dust continents – thinnest at ridge (dust
settling on ocean surface)settling on ocean surface)
5.Youngest rocks are at the center 5.Youngest rocks are at the center and rocks at the edges of the and rocks at the edges of the
Atlantic are 150 million years oldAtlantic are 150 million years old
Active MarginActive Margin Plates Plates
running into running into each othereach other
Volcanoes, Volcanoes, mountain mountain building, building, earthquakesearthquakes
Subduction –one plate moves under Subduction –one plate moves under the otherthe other
Volcano 100 km from trench
South America is moving westSouth America is moving westcolliding with Nazca platecolliding with Nazca plate
Trench ↑ ↑ Mountains
Passive MarginPassive Margin
Growing platesGrowing plates
Volcanic Islands are found only Volcanic Islands are found only at ACTIVE plate boundariesat ACTIVE plate boundaries
Forms LITHOGENIC SEDIMENT- break up Forms LITHOGENIC SEDIMENT- break up of rocks (Quartz)of rocks (Quartz)
Andros Andros nono Quartz – Quartz –nono volcano volcano– Biogenic sedimentBiogenic sediment
Made of skeletons and shells of marine organismsMade of skeletons and shells of marine organisms
Why study plate tectonics?Why study plate tectonics?
What do you find at active boundaries?What do you find at active boundaries?
Minerals – Iron – Oil – Gold - Diamonds
Present active boundaries are easy to find, finding active boundaries pre-dating Pangea requires a lot of study
Active Plate Margin vs Passive Active Plate Margin vs Passive Plate MarginPlate Margin
Active MarginActive Margin- little or no shelf (shelf is - little or no shelf (shelf is crushed by movement)crushed by movement)
therefore minimal amount of fishing (no shallow therefore minimal amount of fishing (no shallow water for plants), EXEPT at upwellingswater for plants), EXEPT at upwellings
Passive plate marginPassive plate margin- very wide shelf- very wide shelf Therefore (shallow water for plants) major fishing, Therefore (shallow water for plants) major fishing,
because of shallow waterbecause of shallow water
Shelf is only 8% of the ocean’s Shelf is only 8% of the ocean’s surface, but the most valuable.surface, but the most valuable.
Average width 40 milesAverage width 40 miles Average depth 197 feetAverage depth 197 feet Slope is undetectable to eye (flat because turbidity Slope is undetectable to eye (flat because turbidity
(Mud) currents from rivers level out the slope(Mud) currents from rivers level out the slope
Biologically riches part of Biologically riches part of the oceanthe ocean
Divisions of oceansDivisions of oceans Benthic –Benthic –
– Topography of the ocean bottomTopography of the ocean bottom Pelagic –Pelagic –
– Water environmentWater environment
Pelagic divisionsPelagic divisions
Photic – Photic – – Lighted areas Lighted areas
where where photosynthesis photosynthesis takes placetakes place
Aphotic –Aphotic –– Light does NOT Light does NOT
penetratepenetrate
Pelagic (water) environment Pelagic (water) environment divided by depthdivided by depth
NeriticNeritic – – water near water near the shorethe shore
OceanicOceanic——water water beyond the beyond the shelfshelf
Deep Deep OceanOcean – – ocean floorocean floor
Neritic (near shore)Neritic (near shore)
Large variety of conditionsLarge variety of conditions
Salinity changes caused by:Salinity changes caused by:EvaporationDilution from freshwater riversDilution from freshwater rivers
Temperature changes- water depthTemperature changes- water depthMOST BIOLOGICALLY MOST BIOLOGICALLY PRODUCTIVE PART OF THE SEAPRODUCTIVE PART OF THE SEA
Oceanic (beyond the shelf)Oceanic (beyond the shelf)
Conditions are more Conditions are more constantconstant
–Slow moving currentsSlow moving currents
–Temperature constant Temperature constant (except in thermoclines)(except in thermoclines)
Deep OceanDeep Ocean
Bathyal – edge of shelfBathyal – edge of shelfAbyssal – deep oceanAbyssal – deep oceanHadal – trenchesHadal – trenches
Environment of Deep OceanEnvironment of Deep Ocean High water pressure??High water pressure??
Food ??Food ??No light – no plants ??No light – no plants ??
Oxygen ??Oxygen ??No light – no plants ??No light – no plants ??
OO22 is brought down by cold water density currents is brought down by cold water density currents
–Organisms are primarily HOrganisms are primarily H22O, because water is O, because water is
not compressible like airnot compressible like air
Most of food falls from the surfaceMost of food falls from the surface
Sea level has risen twice in the Sea level has risen twice in the last 30,000 years.last 30,000 years.
Why has sea level changed????Why has sea level changed????
Glaciers change sea levelGlaciers change sea level