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Striation – linear grooves formed in the surface of some minerals as they grow.
Plate Tectonics
Geologic Time
4600
543
248
65
The Prune Effect - 1800s - (failed attempt 1)
The molten Earth cools and contracts
The crust wrinkles and crumples
Mountains form
What about rift valleys?
What about shape and position of the continents?
Rift Valley
The Expanding Earth – (failed attempt 2)
20th century - radioactive decay
Land masses are ripped apart
Explains the continents
What about the mountains?
- An idea before its time
- Alfred Wegener 1915
- Processor to plate tectonics
Continental Drift
Pangaea - supercontinent
Fragmented and floated around
Pangaea 200 million years ago
Super Continent
Lines of Evidence
•Matching Coastlines
•Matching Geology
•Glacial Deposits
•Fossil Evidence
•Apparent Polar Wandering
Matching
Coatlines
Where is the coastline?
Matching
Geology
The Collision
The Separation
Glacial Deposits
Striations
Fossil Evidence
Glossopteris
Mesosaurus - links South America and Africa during the late Paleozoic and early Mesozoic eras.
Apparent Polar Wandering
A study by S. K. Runcorn in the 1950s, indicated that the magnetic north pole had apparently moved over the last 500 million years, from Hawaii to its present location.
All the parts are in place,
but 1.
How are the continents moving?
The Revolution Begins
early 1960s
RingOf
Fire
Discovery of Midoceanic Ridge
Detailed sea-floor mapping
Harry Hess - essay in geopoetry
* Sea-floor spreading hypothesis
Paleomagnetism
Youngest rock in the center
Unifying Theory - Plate Tectonics
Tectonic cycle- deals with the movement and interactions of the lithospheric plates.
Seafloor Spreading and Plate Boundaries
Plate Boudaries / MarginsDivergent Plate Bounderies
1. continental - rift valleys
Divergent Plate Boundaries
2. ocean - midoceanic ridge / spreading sea floor
Transform Plate Bounderies
San Andreas Fault
Convergent Plate Bounderies
Oceanic - Continental
Oceanic - Oceanic
Continental - Continental
Andes Mountains
Japan, Philippines
Himalaya Mountains
West Coast of United States
Earthquakes, Volcanoes, and Plate Boundaries
Benioff ZoneAssociated with Subduction
How old is the ocean floor?
Driving Mechanism - convection currents