the layers of the earth
DESCRIPTION
The Layers of the Earth. Earth Layers. The Earth is divided into 4 main layers. Inner Core Outer Core Mantle Crust. The Crust. Outer most layer of the Earth The Earth’s crust is like the skin of an apple. It is very thin compared to the other three layers. - PowerPoint PPT PresentationTRANSCRIPT
The Crust Outermost layer of the Earth The Earth’s crust is like the skin of an apple. It is
very thin compared to the other three layers. The crust makes up 1% of the Earth and is called
the “rock and mineral” layer. The crust of the Earth is broken into many pieces
called plates. At the junction of these plates some interesting
things occur!
And what type of crust would you like with your Earth?
• There are two types of crust.– Continental crust– Oceanic crust
Continental Crust
• Makes up the continents
• Contains light colored rocks such as granite.
• Floats high on the mantle
Oceanic Crust
• Makes up the ocean floor
• Contains the dense rocks such as basalt
• Thinner than the continental crust
The Mantle The mantle is the layer between the
crust and the outer core. The mantle is the largest layer of the
Earth. The mantle is made up of MAGMA (hot
molten rock). Because of the heating and cooling of
liquid rock, convection currents occur. These currents force the plates of the crust to move.
Mantle Zones: Lithosphere
• Thin, uppermost part of the mantle and crust; rigid, brittle rock
• Floats on the athenosphere, and slides around very slowly.
• The upper part of the lithosphere melts rocks, forming a substance called magma.
Magma
• Magma (melted rock) moves like hot oatmeal.
• Uneven heating causes material in the mantle to constantly and slowly rise & fall in convection currents.
• Convection Currents: process by which hot fluid rises to the surface, and then sinks again, like soup being heated in a saucepan
Mantle Zones: Asthenosphere
• Hot, weak zone directly under the lithosphere
• Flows at a very slow rate like hot asphalt under a heavy weight
• The movement (convection currents) of the asthenosphere is the reason that the crustal plates of the Earth move
Core
• Deep within the Earth is the core
• The core is made mostly of nickel & iron
• Twice as dense as the mantle.
• Main source of heat that triggers the convection currents
• The core is made of two layers
Outer Core The outer core of the Earth is a ball of
very hot liquid metal. The outer core is made up of mostly
iron and is very dense. Because this liquid metal is moving,
positive and negative particles are created and released that create the Earth’s MAGNETIC FIELD.
Inner Core The inner core of the Earth has
temperatures and pressures so great that the metals are squeezed together and are not able to move.
Therefore; the inner core is a solid. The temperature in the core is nearly as
hot as the surface of the SUN!
Plate Tectonics
• Pieces of the lithosphere that move around
• Each plate has a name• Fit together like jigsaw puzzles• Float on top of mantle similar to ice
cubes in a bowl of water
Continental Drift
http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml
Alfred Wegener 1900’sContinents were once a single land mass that drifted apart.
Fossils of the same plants and animals are found on different continents
Called this supercontinent Pangea, Greek for “all Earth”
245 Million years ago
Split again – Laurasia & Gondwana 180 million years ago
Sea Floor Spreading
• Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins
• Magma rises to thesurface and solidifiesand new crust forms
• Older Crust is pushedfarther away from theridge
How Plates Move
http://pubs.usgs.gov/gip/dynamic/unanswered.html
Different Types of Boundaries
http://pubs.usgs.gov/gip/dynamic/understanding.html
Divergent Boundary – Iceland
http://pubs.usgs.gov/gip/dynamic/understanding.html
Divergent Boundary - Continental
http://www.geology.com
Convergent Boundary – Oceanic & Continental
http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com
Convergent Boundary – Oceanic & Oceanic
http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com
Convergent Boundaries - Continental
http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com