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Edward Seuss
found 4 fern fossils on 4 different continents
earth had no bumps, overtime got old and wrinkly, oceans began to fill in the cracks, over time as it contracted the oceans would fill in the spaces |
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when all the continents fit in as one continent
theory = Alfred Wegener
“could these land masses have been joined together at some distant time and subsequently drifted apart?” |
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| Two seas at the time of Pangaea |
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| Evidence for Pangaea/Continental Drift |
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Definition
Mountains
Glaciers
Fossils
Continental Drift
Ring of Fire ton of earthquakes, thinks it has to do with movement of continents
oceanic crust younger than continental crust
mid-atlantic ridges/mid-ocean ridges |
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| Original Theories on Continental Drift (false) |
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Definition
Continents plow through ocean basins (false)
Continents moved b/e of gravitational attraction of equator and sun/moon (false) |
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Definition
Hydrosphere: 4km thick, ocean
Continental crust: .4 %35-40km, low density rocks (aluminum, silicon, oxygen)
Mantle: 68.1 % 2900 km dense, hot rocks magnesium, iron, silicon, and oxygen
• Core: 31.5% 3500 km
o outer core: liquid
o inner core: solid (iron/nickel) |
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| How pressure affects melting points |
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Definition
Increase in pressure = higher melting point
9900 F melts + pressure: can’t melt*
in order to melt ++ temperature
12000F + 22000F → melt |
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Thick, light: 2.7 g/cm3
Granite
Course texture
light
rest on upper mantle
30-40 km thick |
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Thin, dense: 3.0 g/cm3
Basalt
Dark
Fine texture
rest on upper mantle
4-10 km thick |
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| layer that oceanic crust and continental crust rests on |
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| if weight added or removed from object floating, equilibrium disturbed! |
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| the vertical mvmt of the crust, result of the buoyancy of the earth’s lithosphere as it floats on the denser plastic-like asthenosphere below |
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Canada depressed from 1640-2300 ft below its present level under cover of ice 1.2-1.9 miles thick
sea level rise problems |
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During WWII left his depth recorder on all the time
Saw seam-like structure that ran all over the oceans (mid-ocean ridges)
Underneath the ocean in the worlds longest mountain chain
• Less sediment at mid-ocean ridges
• Gets thicker with sediment as you move away
• A lot of sediment by India: a lot of rivers dump sediment
• More sediment: near land and rivers
• Mountains in oceans had tops flattened out
• Oldest seafloor rock = 180 mil yr old
• Oldest continental rock = 4 billion |
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Definition
Sea Floor Spreading
New ocean crust formed at ridges
Volcanoes that form along the ridge that are originally close to the surface wherever they can be eroded and flat on top
Deep ocean trenches are where the seafloor finally descends back into the mantle
Mud and sediments deposited on the ocean floor are thin toward the mid-ocean ridges is because the age of the seafloor gets younger thus less and less time to accumulate sediments (ESSAY Q) |
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| Drummond Matthews/Fred Vine: |
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Definition
Measured the first magnetic anomalies in the Indian Ocean
N./S. poles’ ocean floor: measure magnetic field
A history of plate movement has been captured in residual magnetic fields
• Magnetite: formed form cooling magma that contains iron oxide
• Particles line up where whichever field is dominant
• Magnetic anomalies: stripes of magnetism were a historical record of new sea floor
• Earth’s magnetic field:
o N. geographic pole = S. magnetic pole (magnets: opposite)
o S geographic pole = N. magnetic pole |
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Earth’s magnetic field: flips every 200,000 years on average
What’s going to happen after the flip:
Organisms can deal with that
Whales use magnetic particles trapped in rocks to navigate
Bacteria can line up along magnetic field |
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sea floor spreading
Buoyant magma pushes up the middle of the ocean’s ridge
As it rises to the surface it pushes the two plates to the side of it |
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sea floor spreading
As magma is raised the heavy parts of plates sink to the bottom |
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sea floor spreading
Constantly recycling the sea floor because of ridge push and slab pull
Underneath moving all the time |
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| areas close to continents |
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Term
| divisions of continental margins |
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Definition
Shelf: average width (60km) break on average around 130 m water depth (ranges too-deeper than 200m)
Slope: lies at water depth (2-3km) submarine canyons
Rise: broad underwater plain |
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Definition
abyssal plain: flattest ares on earth, broad ares of land derived sediments at depths of 3-5 km
abyssal hills: domes, elongated hills, no bigger than 1000m, volcanic rock, think cover of sediment from water above
seamounts: type of mountain
deep sea trenches: |
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| heat passing through a substance |
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| flow of the heated material itself (air, water, molten rock) |
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radioactive decay
objects from space hitting the earth |
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| TAKE A MINUTE TO LOOK FOR THE MAP SHE WAS SAYING WOULD BE ON THE EXAM OF DIVERGENT AND CONVERGENT BOUNDARIES |
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Definition
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2-12 cm (1-5 inches)
as fast as your fingernails grow |
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plate movement
plates are moving away from each other |
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plate movement
plates are moving toward each other |
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plate movement
plates are running parallel to each other |
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Term
| divergent plate boundaries |
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Definition
Boundaries between plates moving apart
Divergent ocean crust; example mid ocean ridge
Divergent continental crust: for example, the rift valley of e. Africa
E. Pacific rise 16.5 spread a yr----high
Earthquakes at divergent boundaries: amount of energy released is related to spreading rate
Faster the spreading --- less energy is released in each earthquake
E. Pac rise = 4.5 Mid at ridge = 6
Continental rifting
Examples: east Africa rift valley, gulf of California, red sea |
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| convergent plate boundaries |
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Definition
Regions where plates are pushing together
Ocean-Continent
Andes Mountains
Ocean-Ocean
One plate being destroyed by subduction under another
Ex) aleutian islands
Continent-Continent
Collision
Plates are of similar material
Ex) Himalayas |
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Term
| transform plate boundaries |
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Definition
Strike/slip: two plates moving past each other
Sea floor not created/destroyed
San andreas fault: transform boundary
No way for California to fall off continent |
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