Earth’s Structure

Layers of the Earth CRUST MANTLE CORE

LAYER 1 CRUST outer most layer thinnest layer consists of loose rocks and soil 2 types of crust continental-dry land oceanic- ocean floor

LAYER 2 MANTLE thickest layer carries the most mass hot solid rock

LAYER 3 and 4 CORE inner or center layer 2 parts outer core- liquid layer that contains melted iron and nickel inner core- solid layer that contains solid iron and nickel

RESTLESS CONTINENTS

ALFRED WEGENER THEORY OF CONTINENTAL DRIFT The idea that the continents were once part of a giant land mass. The one giant land mass is called “PANGAEA.”

WEGENER’S EVIDENCE Fossil Evidence fossils are remains of living things that lived long ago. similar fossils have been discovered in matching coastlines on different continents.

Mountain Evidence some mountain ranges on different continents seem to match. mountain range in eastern Canada seems to match one found in Norway and Sweden.

Rock Evidence The age and kind of rocks and minerals along the edge of one continent match rocks and minerals along the edge of another continent.

THEORY OF PLATE TECTONICS Earth’s lithosphere is divided into tectonic plates that are in constant, slow motion, driven by convection currents in the mantle.

CONVECTION CURRENTS The movement of a gas or a liquid caused by differences in temperature. Hot material from deep within the Earth rises while cooler material near the surface sinks

Sea-Floor Spreading The proof of sea-floor spreading supported Wegener’s original idea.

Takes place at Mid-ocean ridges. Sea-floor spreading is the process by which new oceanic lithosphere is created as older materials are pulled away. Takes place at Mid-ocean ridges. Mid-ocean ridges are underwater mountain chains that run through Earth’s ocean basins. Mid-Atlantic Ridge.

TECTONIC PLATES Pieces of the lithosphere that move around on top of the asthenosphere. Carry the continents, parts of the ocean floor, or both.

MAJOR TECTONIC PLATES NORTH AMERICAN SOUTH AMERICAN PACIFIC INDIAN AUSTRAILIAN ANTARCTIC EURASIAN

plate movement As the plates move, they produce changes in Earth’s surface, including volcanoes, mountain ranges, and deep-ocean trenches.

The edges of different pieces of the lithosphere meet at lines called plate boundaries FAULTS edges of different pieces of the lithosphere form at these boundaries

DIVERGENT BOUNDARIES When two tectonic plates move away from one another.

Sea-floor Spreading When the plates pull apart, magma rises and fills in the gap. At mid-ocean ridge, the rising magma cools to FORM NEW OCEANIC LITHOSPHERE.

Continental Rift When two continental plates pull away. The continents form a RIFT.

Divergent Boundaries © All Rights Reserved. Diverging Africa

Diverging Iceland

CONVERGENT BOUNDARIES When two tectonic plates push into one another.

Continental vs. Continental When two continental crustal plates collide, the continents buckle upward and form mountains.

Himalayas- Asia

Oceanic vs. Continental The oceanic plate slides under the continental plate. The continental crust crumbles and forms new mountains.

Oceanic vs. Continental Ex: Andes mtn in S. America Cascade Mtns. in N. America- Mt. St. Helens

Oceanin vs. Oceanic Two oceanic plates collide, one of the oceanic plates slides under the other. also called a subduction zone

Oceanic vs. Oceanic Hawaiian Islands

TRANSFORM BOUNDARIES When two tectonic plates slide past each other horizontally. Produce EARTHQUAKES.

San Andreas Fault

New Madrid Fault

WHICH TYPE OF BOUNDARY? Rift forming in Iceland San Andreas Fault in California

WHICH TYPE OF BOUNDARY?