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.

• 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.

Earth’s Tectonic Plates

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

Evidence of Pangaea

Continents Fit Together

South America and Africa

Similar Fossil Records

Similar Mountain Ranges

Similar RocksRock Striations Match

Other Evidence - 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.

Sea Floor SpreadingNew crust is formed at mid-ocean

ridges spreading the sea floor

Mid-Atlantic Ridge

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

Tectonic Plate Boundaries

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.

Mid-Atlantic Ridge

Transform Boundaries

• Tectonic plates slide past each

• Forms Fault lines

• San Andreas Fault in California

Volcanoes and EarthquakesMost Occur at Tectonic Plate

Boundaries

Ring Of Fire

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

Hawaii 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”

Yellowstone