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Grade 6: The Restless Earth (Plate Tectonics (What discoveries support the…
Grade 6: The Restless Earth
Earth's Layers
What are Earth's compositional layers (based upon chemical composition)?
Crust
Mantle
Core
What are Earth's physical layers (based upon physical properties)?
Lithosphere
Asthenosphere
Mesosphere
Inner and outer core
Plate Tectonics
What evidence suggests that continents move?
Fossil evidence
Mountain evidence
What is Pangaea?
The continents were joined in a single land mass about 245 million years ago.
What discoveries support the idea of continental drfit?
Magnetic properties of the sea floor
Sea-floor rock contains magnetic patterns that form mirror images on either side of a mid-ocean ridge.
Sea-floor spreading
Molten rock from inside the Earth rises through cracks in the ridges, cools and forms new oceanic crust.
Ocean trenches
Older ocean crust is being destroyed at the same time as it is created as it moves down deep ocean trenches.
Age of the sea floor
Even the oldest ocean crust is young compared to continental crust.
What is the theory of plate tectonics?
It describes the large-scale movement of the Earth's lithosphere which is divided into pieces called tectonic plates.
What are three types of plate boundaries?
Divergent boundaries
Transform boundaries
Convergent boundaries
Mountain Building
What are three kinds of mountains?
Folded mountains form when rock layers are squeezed together and pushed upward.
Volcanic mountains form when melted rock erupts onto the Earth's surface.
Fault-block mountains form when tension makes the lithosphere break into many normal faults.
Vocanoes
What is a volcano?
Magma
Lava
Vent
Where do volcanoes come from?
At divergent boundaries
At convergent boundaries
At hot spots
Earthquakes
What is an earthquake?
Focus
Epicenter
Seismic waves
What causes earthquakes?
Elastic rebound (when rock returns to its original shape after elastic deformation) causes the sudden snap of an earthquake.
