class 1: plate tectonics review today’s topics: earth’s compositional layers plate tectonics:...
TRANSCRIPT
Class 1: Plate Tectonics Review
Today’s topics: Earth’s compositional layers Plate tectonics: theory & actions
Earth’s Compositional LayersAtmosphere & Hydrosphere
Crust
Mantle
Core
Earth’s Atmosphere & Hydrosphere
Earth’s Crust
more dense
relatively light
CRUST
Earth’s Mantle
MANTLEmore densethan crust
CRUST
Earth’s Core
highestdensity
CRUST
MANTLE
CORE
Earth’s Magnetic Field
rocky core
Earth
Requirements for magnetic field: 1. rotation
2. heat flow, convecting fluid3. a mobile conductor (iron or metallic hydrogen)
Global Earthquake Locations
Global Volcano Locations
Linking Observations
Continental Drift
Continental Drift (movie)
Ages of the Ocean Floor
Ma = Million years ago
1 billion years = 1 Gyr1 million years = 1 Myr
1 thousand years = 1 kyr
Heat Flow
Warm colors = higher heat flow
Cool colors = lower heat flow
high atocean ridges
Global Topography and Bathymetry
oceanridges
The Puzzle Solved…..
earthquake locations volcano locations
sea floor age sea floor bathymetry
+ heat flow too!
Earth’s Tectonic Plates
Earth’s Tectonic Plates (movie)
Lithosphere & Asthenosphere
Plate Boundaries
Divergent Plate Boundaries
Seafloor Spreading (movie)
Convergent Plate Boundaries
1 2
3
Seafloor Subduction (movie)
Transform Plate Boundary
strike-slipfaulting
Transform Faulting (movie)
Plate Boundaries
Hotspots
Hot Spots
hot spot trail
Hot (not molten) rising plume
lithosphere
Direction of plate Direction of plate motionmotion
Formation of Island Chains
V1
V1
melting at base of crust
V1
Example: The Hawaiian Chain
Fixedhot spot
• Earth’s crust is divided into plates• Plates move relative to one another at 1-15 cm/yr• Plate interiors are largely undisturbed• Deformation is concentrated at plate boundaries
Consequences:• Plate tectonics constantly change Earth’s surface• Earthquakes occur mostly at plate boundaries• Volcanoes occur mostly at plate boundaries
Basic Premise of Plate Tectonics
1. Examine volcanic rocks Q: what was the source for magma?
How do we explore Earth’s interior?
2. Observe seismic waves from earthquakes Q: where are the layers, what are their densities?
3. Examine meteorites Q: what are they made of? like the core?
4. Existence and behavior of geomagnetic field Q: what is the core doing?
• Satellites 1 (Moon)• Size (radius) 6378 km• Bulk density 5.5 g/cm3 (4.1 g/cm3uncompressed)
• Surface gravity 9.8 m/s2
• Tectonism, volcanism yes (today)• Rotation 1 day• Orbit 365.25 days• Atmosphere 78% N2, 21% O2
• Surface pressure 1 atm• Surface temperature 20°C (diurnal, seasonal changes)
• Plate tectonics yes• Water yes
Earth