sea floor spreading and plate tectonics
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Sea Floor Spreading and Plate Tectonics. Chapter 1.4 and 1.5. Ch. 1.4 Sea-Floor Spreading. Mid-Ocean Ridge longest chain of mountains in the world all below the ocean Scientists use SONAR to map them. SONAR -a device that records echoes of sound waves History of Ocean Drilling. - PowerPoint PPT PresentationTRANSCRIPT
Sea Floor Spreading and Plate Tectonics
Chapter 1.4 and 1.5
Ch. 1.4 Sea-Floor Spreading
Mid-Ocean Ridge• longest chain of mountains in
the world
• all below the ocean
• Scientists use SONAR
to map them
SONAR -a device that records echoes of sound wavesHistory of Ocean Drilling
2. Sea-floor spreading?
• At the mid-ocean ridge, molten material rises from the mantle and erupts. The molten material then spreads out, pushing older rock to both sides of the ridge.
Earth's Volcanic History
3. Scientists found Evidence
Molten Material found
• as pillow-shaped rocks
• hardened quickly
3. Scientists found
Evidence
Magnetic patterns or stripes found in
• Ocean floor rock
• Reversals of Earth’s magnetic field
3.3. Scientists found
Evidence
Drilling core samples
• age of rock samples
• The farther away from the mid-ocean ridge, the older the rocks
Drilling for Cores Samples
4. Subduction at Deep-Ocean Trenches
• Subduction:
a process where the ocean floorsinks beneath a deep-ocean trenchand back into the mantle…over tens of millionsof years.Sketch this picture
5. Subduction at Earth’s Oceans
Drilling in the Arctic Ocean
Ch. 1.5 Theory of Plate Tectonics
Plate Motion• Pieces of Earth’s lithosphere are in constant
slow motion• Driven by convection currents in mantle• Theory of Plate Tectonics explains the
§ Formation§ Movement§ Subduction of Earth’s plates
Plate Boundaries
• Plate boundaries are- where edges of lithosphere meet
• Faults are- breaks in the crust, where rocks that slip past each other form at plate boundaries
3 Types of Plate BoundariesTransform boundaries
• Where 2 plates
slip past each
other
Plate boundariesDivergent boundaries
• Where 2 plates move apart
• A rift (deep) valley forms
2. Plate boundaries Convergent
• Where 2 plates come together or collide
The plate density determines which plate goes under-subduction
Where continental crusts collide-it forms mountains
Plate boundaries
Continent’s Slow Dance
• 225 million years ago, plates joined together- Pangaea
• 180-200 mya Continents split apart, narrow seas become oceans
• 135 mya Continents began to drift apart• 65 mya India a separate continent,
Australia connected to Antarctica
• Today continents look like puzzle pieces that once were together
Take Aim At Climate Change