Plate Tectonics Wrap-Up Fit of the Continents. Paleoclimate & Glaciers Ancient climatic zones and...
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Transcript of Plate Tectonics Wrap-Up Fit of the Continents. Paleoclimate & Glaciers Ancient climatic zones and...
Glossopteris Fossils
These seeds are very large and do not float in water, so
how could they have survived transport
to all these different continents?
The Theory of Plate TectonicsThe continents are riding along on tectonic plates,
which move across the Earth’s surface driven by mantle convection (the very slow “boiling” of the mantle beneath the crust).
Three types of plate boundaries
• Divergent – plates are moving apart from one another. – Ex: Mid-Ocean Ridges
• Convergent – plates are colliding with one another. – Ex: Nazca plate and South American plate pushing up the
Andes. – Ex: Indian plate and Asian plate colliding to form the
Himalayas
• Transform – plates are sliding past one another– Ex: Pacific plate and North American plate moving past one
another along the San Andreas Fault
Divergent boundaries
Hot mantle material rises up and causes the crust to thin and move apart.
Mainly found in the middle of oceans • shallow, weak earthquakes• very few volcanoes• high topography on the sea floor• the youngest sea floor crust
Convergent boundaries•Deep trench on ocean side and then high elevations toward continent.•Shallow to deep earthquakes as you move toward continent.•Arc of volcanoes on the continent side.•No age relationship
Convergent boundariesOcean crust always moves below continental crust because ocean rocks (basalts) are more dense than continental rocks (granites).