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Our Amazing Planet. Planet Earth. Earth’s Layers. Crust. Earth’s thin outermost layer. Continental Crust (land) - thick low density rock (granite). Oceanic Crust (sea floor)- thin dense rock (basalt) . Mantle. Earth’s thickest layer made of dense iron-rich super heated soft rock. - PowerPoint PPT Presentation
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Crust
• Earth’s thin outermost layer.
–Continental Crust (land) - thick low density rock (granite).–Oceanic Crust (sea floor)- thin dense rock (basalt)
Mantle
• Earth’s thickest layer made of dense iron-rich super heated soft rock.
• Where convection currents occur.
Core
• Earth’s innermost layer made of hot, dense iron and nickel.
–Outer core - Liquid–Inner core - Solid
Lithosphere
• Earth’s outermost layer• Includes the crust and solid upper
part of the mantle.• Divided into huge pieces called
“Tectonic Plates”.• Move around on top of the
asthenosphere - very hot, soft layer of the mantel.
Continental Drift
–Theory that the Earth’s continents move over time–Proposed by Alfred Wegener in the early
1900’s–Evidence of Continental Drift:• Continents fit together• Similar fossils records• Similar rocks and minerals• Similar rock formations and striations• Similar climatic conditions –
Glaciations
Sea Floor Spreading
• Occurs where tectonic plates spread apart at Mid Ocean Ridges
• Magma rises from inside the Earth creating new sea floor.
• New sea floor pushes the existing sea floor out explaining why continents move.–Evidence that supports the theory of Continental Drift.
Convection Currents in the Mantle
• Causes Sea Floor Spreading – The main cause
of plate tectonics
• Convection Currents– Hot magma rises
and cooler magma sinks in the Earth’s Mantel
Convergent Boundaries
• Tectonic plates collide -
• Forms trenches, mountains, and subduction zones
• CTMS – Convergent – trenches – mountains - subduction
Convergent BoundariesSubduction Zones
Creates trenches in the ocean and mountains and volcanoes on land
Divergent Boundaries
• Tectonic plates move apart
• Forms Mid Ocean Ridges in oceans and Rift Valleys on land
• East African Rift
• Mid-Atlantic Ridge
Mid-Ocean Ridges
• Chain of volcanoes at the middle of the ocean floor.
• Causes Sea Floor Spreading• Magma comes up from inside the
Earth, cools and hardens and creates new sea floor.
• The rock at the mid-ocean ridge is the youngest and gets older as it moves farther away from the ridges.
Transform Boundaries
• Tectonic plates slide past each
• Forms Fault lines
• San Andreas Fault in California
Ring of Fire
• Volcanoes around the Pacific Ocean caused by tectonic plates colliding into each other creating subduction zones at CONVERGENT boundaries.
Hot Spots
• Areas in the middle of tectonic plates where magma inside the Earth rises through the crust and forms volcanoes.
• Like the Hawaiian Islands
Super Volcano
• Yellowstone National park–Underground volcano caused by
another Hot Spot
• 3 overlapping calderas underground is believed to have formed from a hot spot creating Yellowstone’s “Super Volcano”