1. Continental Margins Continental shelf: shallowest part of the margin
Continental Slope: a steeper part
Continental Rise: gently sloping region at the base of the of the continental slope; consists of sediment that piles up on the sea floor

2. Deep Sea Basins Abyssal plain: flat area
Seamounts: old volcanos and islands
Trenches: deepest part of the ocean
Mid Oceanic Ridge: main feature of the ocean floor
Central Rift Valley: great gap at the center where plates are pulling apart

3. Structure of Earth
Earth Originated 4.5 billion years ago by the Big Bang
Earth’s materials were sorted by density
Densest is found at the center and the least on the outside

4. Structure of Earth Internal Structure
Inner Core: composed of Fe Ni, high pressure and temperatures reach 5,000oC; solid in nature
Outer Core: Same elements and temperature but less pressure so is a liquid
Mantle: Contains Si and O, semi-solid state that moves like molasses
Asthenoshere-upper mantle
Crust: outermost layer, extremely thin, rigid skin floating on the mantle (Oceanic and Continental)
Lithosphere-uppermost mantle and crust

5. Earth’s Crust Oceanic Crust Continental Crust Consist of Basalt
200 myo
Dense and thin
Continental Crust
Consist of granite
3.8 byo
Not dense and thick

6. Continental Drift Proposed in 1920 by Alfred Wegener
Theory: states that all the continents had once been joined in a single super continent called Pangaea, 180 mya
Wegener was laughed at due his inability to proposed a mechanism for the movement of continents

7. Continental Drift Evidence Coal deposits geological formations
fossils match up on opposite sides of the Atlantic
Jigsaw puzzle like appearance of continents
Glacial rock deposits
Limestone and salt deposits

8. Seafloor Spreading Evidence
Discovery of the Mid Ocean Ridge
Discovered using sonar
Interrupted by large geological fault called transform faults
EX: Mid-Atlantic Ridge and East Pacific Rise

9. Seafloor Spreading Evidence
Magnetic Reversals
Discovered by the Glomar Challenger in 1968
Symmetric Pattern of Magnetic Bands in the seafloor from reversals of the magnetic poles
Opposite matching bands on either side of mid-oceanic ridge

10. Seafloor Spreading Evidence
Sediment Age and thickness
Discovered by the Glomar Challenger
Thickest and oldest sediments are found farthest from the Mid Ocean Ridge

11. Seafloor Spreading Proposed by Henry Hess in 1960’s
Theory: states that mantle rises up at the Mid Ocean Ridges is then cooled, placed on the seafloor and moved towards the continents
Mechanism was thought to be convection of the mantle beneath the seafloor

12. Plate Tectonics
Combination of Continental Drift and Seafloor Spreading
Theory: earth’s surface is covered by a fairly rigid layer composed of the crust and the uppermost part of the mantle called the lithosphere that is broken into plates which move over the mantle

13. Plate Collisions Oceanic Plate to Oceanic Plate
Causes trenches, earthquakes, volcanoes and island arcs
EX: Aleutian Island in Alaska

14. Plate Collisions Oceanic Plate and Continental Plate
Creates a trench, earthquakes, continental volcanoes
Seafloor is destroyed at the trench which explains why the seafloor is so young

15. Plate Collisions Continental Plate and Continental Plate
Create mountains
EX: Himalayan Mountains

16. Plate Movements Apart: plates do move apart and create new crust
EX: mid ocean ridge and Iceland
Shear Boundary: plate are able to slide past each other
EX: California’s San Andreas Fault

17. Marine Sediments Hydrogenous Cosmogenous Lithogenous Sediment
Result from chemical reactions within seawater
Cosmogenous
Result from outer space
Lithogenous Sediment
Formed from the weathering and erosion of rocks
Biogenous Sediment
Created from the skeleton or shells of marine organisms
Calcareous: made of calcium carbonate
Siliceous: made of silica

18. Hot Spots Stationary plume of magma under a moving plate
Creates volcanic islands in the middle of plates
EX: Hawaiian Islands and the Emperor Seamount Chain