Plate Tectonics Definition Plate Rigid rocky outer surface
- Slides: 33
Plate Tectonics
Definition Plate: Rigid, rocky outer surface of the Earth Tectonic: To build or destroy The processes by which the rocky plates of the planet move and interact with each other
Internal Structure of the Earth lithosphere plates inner core solid iron mantle hot dense rock outer core liquid iron
Lithospheric Plates Oceanic: Continental: thin, heavy, mostly lava flows thick, light, mostly granite Asthenosphere Weak, plastic upper mantle
Lithospheric Plates
Diverging Plate Boundaries Where plates pull apart from each other Stretching & thinning High heat flow (New Crust Created)
Diverging Plate Boundaries Key landform: mid-oceanic ridges volcanic mt. ranges axial valley 1000’s miles long 1 -2 miles tall
Converging Plate Boundaries Where plates collide Subduction zone: collision between oceanic and continental lithosphere (Crust Destroyed)
Subduction zones Key landforms: trenches & volcanic arcs
Transform Plate Boundaries Where plates slide side by side Key landform: faults (Crust neither destroyed or created)
Driving Force thermal convection / convection currents pushes up at ridges plates spread away hot rock cold rock plate sinks and subducts
Geologic activity at plate margins Volcanism: C, D Earthquakes: C, D, T Rock Deformation: C, D, T
Evidence: shape of continents The margins of some continents look like they could fit together First proposed by Alfred Wegener
Fossil Evidence
Evidence: volcanoes Nonrandom occurrence of volcanic activity
Evidence: earthquakes Nonrandom occurrence of earthquakes Shallow at diverging margins deep at converging margins
Evidence: hot spots Stationary upwellings of heat away from plate margins
Evidence: hot spots As plates move, the volcanoes are carried away from the hot spot Only volcanoes near the hot spot are active Can determine direction and speed of the plate motion
Evidence: age of seafloor rocks Youngest rocks are found at the mid oceanic ridges Oldest rock are found farthest from the ridge
Evidence: paleomagnetism Earth has a strong magnetic field Iron rich volcanic rocks record Earth’s magnetic field at the time they form
seafloor paleomagnetic record Bands of alternating polarity Symmetrical about the mid oceanic ridges
seafloor paleomagnetic record lava forming at the ridges picks up the current magnetism, then gets pushed out of the way as newer lava forms Records of the growth and spreading of the seafloor
seafloor paleomagnetic record The alternating polarity represents complete reversals of Earth’s magnetic field
continental paleomagnetic record The location of magnetic poles on separate continents appear to wander with time If the poles haven’t moved significantly, then the continents did Use overlapping poles to reconstruct the past positions of the continents
Plate Tectonics in the PNW Cascadia subduction zone
Plate Tectonics in the PNW Cascades volcanic arc
Plate Tectonics in the PNW Juan de Fuca & Gorda mid ocean ridges
Plate Tectonics in the PNW Blanco & Medocino fracture zones
Plate Tectonics in the PNW “exotic terranes islands carried by the plates Attached to the North America continent
seafloor paleomagnetic record Bands of alternating polarity Symmetrical about the mid oceanic ridges
Evidence: paleo-environments
Evidence: distribution of mountains
Importance of Plate Tectonics
- Plate tectonics definition
- Plate tectonics definition apes
- Inner core and outer core
- Non-rigid transformations
- Rigid dam
- What is rigid and non rigid
- Rigid outer covering of plant cells
- Plate tectonics vs continental drift
- What are the four types of boundaries
- Evidence of the theory of plate tectonics
- Plate tectonics theory states that
- Continental drift theory and plate tectonics theory
- Compare continental drift and plate tectonics
- Continental drift webquest
- Plate tectonics vocabulary worksheet
- Continental drift
- Mantle convection and plate tectonics
- Driving force of plate tectonics
- Plate boundaries
- Summarize the theory of plate tectonics
- Harry hess and seafloor spreading
- Continental drift theory and plate tectonics theory
- Mantle magma
- Collision plate boundaries
- Edible plate tectonics
- A plate tectonics puzzle worksheet answer key
- From now
- Fossils as evidence of continental drift
- Francis bacon plate tectonics
- Oreo cookies and plate tectonics answer key
- Plate tectonics interactive lab
- Divergent boundary oreo
- Two regions of the mantle
- Explain the theory of plate tectonics.