Earth*s Interior - Mr. Cramer Download

Transcript
 Could you watch an island grow?
The islands of Hawaii
Exploring Inside Earth
 Earth is constantly changing.
 Earth looks different today than it did millions of years ago.
 What’s inside Earth?
 Very hard to answer, because you cannot just dig a hole to
the center of the Earth.
 You would have to dig over 6,000 kilometers to reach the
center of the Earth.
 Geologists use two type of evidence
 Direct evidence – rock samples
 Indirect evidence – seismic waves
Evidence From Rock Samples
 Study rocks from inside Earth
 Geologists have drilled holes up to 12 kilometers deep
 Geologists can suggest what conditions are deep inside
Earth
 Forces deep inside Earth sometimes blast rock to the
surface from depths more than 100 kilometers deep,
providing more information.
Evidence From Seismic Waves
 Indirect method of observation
 When earthquakes occur, they produce seismic waves
 The speed of the seismic waves and the paths they take
reveal the structure of the planet
 From seismic waves they have learned that Earth’s
interior has several layers
A Journey to the Center of Earth
 3 main layers of the Earth
 Crust
 Mantle
 Core
 Layers very in Size, Composition and Temperature
 The temperature is heat left over from the formation of
the planet
 Radioactive substances inside Earth creates heat
 Weight from the rock above causes an increase in the
pressure as you get deeper
The Crust
 The Crust is Earth’s outer layer – land and ocean floor
 Thickest under high mountains, thinnest beneath the
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ocean
Crust is 5 to 40 kilometers thick, up to 70 kilometers
beneath mountains
Oceanic crust is the crust beneath the ocean, made of
rocks such as basalt
Basalt – dark rock with a fine texture
Continental crust – land is mainly granite
Granite – light color with a coarse texture
The Mantle
 About 40 kilometers beneath the surface, you cross
into a solid material the mantle a layer of hot rock
 Mantle has 3 layers, very hot rock, about 3,000
kilometers thick, and layers based on physical
characteristics
 Lithosphere uppermost part similar to the crust,
 The uppermost part of the mantle and the crust together
form the rigid layer called the lithosphere
 Averages about 100 kilometers thick
 Asthenosphere below the lithosphere, hot and
increased pressure
 Soft than the rock above
 Can bend like plastic
 Still solid rock
 The Lower Mantle
 Extends all the way to the Earth’s core
Core
 The Core is mostly made of metals iron and nickel
 Two parts of the core
 liquid out core
 solid inner core
 Inner and outer core are about 3,486 kilometers thick
Outer core and Inner Core
 Outer Core – layer of molten metal surrounding the
inner core (Liquid)
 Inner Core – dense ball of solid metal, great pressure
pressing the iron and nickel go much it cannot become
liquid
The Core and Earth’s Magnetic Field
 Scientists think that the liquid outer core creates the
Earth’s magnetic field
 Magnetic field affects the whole Earth
 A compass needle aligns with the line of force in
Earth’s magnetic field
Questions
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Why is it difficult to determine Earth’s inner structure?
How are seismic waves used to provide evidence about
Earth’s interior?
List Earth’s three main layers.
What is the difference between the lithosphere and the
asthenosphere? In which layer is each located?
Classify each of the following layers as liquid, solid, or solid
but able to flow slowly: lithosphere, asthenosphere, lower
mantle, outer core, inner core.