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Striation – linear grooves formed in the surface of some minerals as they grow.
Plate Tectonics
65
248
Geologic Time
543
4600
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?
Continental Drift
- An idea before its time
- Alfred Wegener 1915
- Processor to plate tectonics
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
Ring
Of
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 / Margins
Divergent 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
Andes Mountains
Oceanic - Oceanic
Japan, Philippines
Continental - Continental
Himalaya Mountains
West Coast of
United States
Earthquakes, Volcanoes, and
Plate Boundaries
Benioff Zone
Associated with Subduction
How old is the ocean floor?
Driving Mechanism - convection currents