Earth’s Layers 6.E.2 Notes

Anatomy of Earth Crust Mantle Outer Core Inner Core

Crust Mostly made up of rocks and minerals covered by water, sand, soil, and ice This layer is solid Thinnest layer; Makes up less than 1% of the earth’s mass

Crust 3-25 miles thick It is the least dense layer Temperature is the same as the air because it meets with our atmosphere

Crust The crust consists of continental plates and oceanic plates When continental crust (6 to 47 miles thick) meets oceanic crust (4 miles thick) it forms a subduction zone (when two plate tectonics collide)

Questions What is the density of the crust? It is the least dense layer of the earth, makes up less than 1% of Earth’s mass What does it mean when we say less dense or more dense? Density is mass/ volume. When something is less dense it tends to float, whereas more dense objects tend to sink How thick is the crust? It is the thinnest layer of the earth, 3-25 miles thick Is the crust solid, liquid, or gas? Solid What is the crust made of? Rocks and minerals What is the crust’s temperature? The same temperature as the atmosphere

Lithosphere and Asthenosphere

Lithosphere/ Asthenosphere Lithosphere Is the crust and uppermost part of the mantle Forms a rigid shell on the outside of Earth. The rocks in the lithosphere are strong and do not bend easily It is broken into large pieces called tectonic plates Asthenosphere Is the partially melted portion of the mantle below the lithosphere It is hotter than the lithosphere and can bend more easily. The ability of the asthenosphere to bend is related to tectonic plate movement.

Naming tectonic plates Tectonic plates are named based on its ability to move in relation to another plate. There are over 30 tectonic plates but scientist have identified 15 large plates. We live on the North American plate which is made up of: – Oceanic Crust – Continental Crust Tectonic plates are called: –Divergent: two plates move away from each other –Convergent: two plates move toward each other –Transform: two plates slide past each other.

Convergent Boundaries: The plates become crumpled and deformed. Due to neither plate subducting, blocks of crust slide upwards creating tall mountains. The plates do not crumple or deform as they push towards each other. As the mantle near the subducted plate melts, magma rises and forms a volcanic arc on the plate that does not subduct. No subduction Subduction Zone When tectonic plates move under another plate

Convergent Subduction Zone Oceanic and Continental Plates When an oceanic plate encounters a continental plate, the oceanic plate plunges beneath the other plate.

Oceanic Plate Tectonics

Continental Tectonic Plates No Subduction Zone

The effects of subduction zones Mountain ranges can be created by subduction zones. Subduction zones are at high risk for earthquakes.

Transform Boundaries: Creates Earthquakes Divergent BoundariesDivergent Boundaries: Forms valleys

What causes tectonic plates to move? They move because of convection, which happens in the Earth’s asthenosphere. Convection in the mantle can drag plates over Earth’s surface. The rocks in the mantle are not hot enough to bend easily but they can flow in away similar to fluids.

Mantle Layer between crust and core Thickest layer of the earth 1800 miles thick Made up of dense, hot molten rock (mainly iron and magnesium) Between degrees F A convection current takes place in the mantle Causes pieces of the crust to move It is mostly solid

Mantle The mantle is split into upper mantle and lower mantle The lithosphere is made up of the upper mantle and the crust The asthenosphere is below the lithosphere

Mantle The lithosphere contains ridged rocks The asthenosphere contains rocks that can flow like a liquid In the mantle we have two layers of solid rock with heated flowing rock between them

Let’s Review

The Earth’s crust is divided into 12 major tectonic plates These plates sit on the dense, hot, layer of the earth known as the lithosphere Lithosphere = the crust and upper portion of the mantle

The Earth’s plates move about 2 inches per year (5 centimeters) Convective currents within the mantle cause the plates to move As they move, the plates: – Press against one another (convergent boundary) – Pull apart from one another (divergent boundary) – Scrape against one another (transform boundary)

Plate boundaries……

What is convection? Mws Mws

Convection currents in the earth

Continental Drift Continental Drift Alfred Wegener was a meteorologist that believed that at one period of time the continents were all connected. People didn’t believe him because he didn’t have enough evidence to support his theory of the continents were moving because people couldn’t feel it. He believed over time the continents split into separate pieces and shifted around the world. His theory was called the “Continental Drift”. He wasn’t the first to announce this theory; however, he was the first to have evidence: Plants and animals Pangea

Effects of Tectonic Plate Boundaries Major geological events occur at these plate boundaries: – Earthquakes Earthquakes – Volcanic Eruptions Volcanic Eruptions – Mountain Building

New mountain ranges are being formed where: – two continental plates press against one another – An oceanic plate and a continental plate press against one another

Thin oceanic plates spread outward at areas known as mid-ocean rift zones.

Scientists who study how wave energy travels through the different layers of the Earth are called Seismologists.

Remember…. Waves have characteristics such as: the number of waves that pass a given point in 1 second Frequency (speed of the wave) the height from the rest position to the bottom of the trough or from the rest position to the top of the crest Amplitude Distance from crest to crest or trough to trough Wavelength

Transverse waves…..

Earthquake: Seismic Waves Earthquake: Seismic Waves Write in notebook…. During an earthquake, energy is released into the Earth as: -Primary waves (compression waves) -Secondary waves (shear waves) -Surface waves

Write in notebook Write in notebook Primary (P) waves travel through both solid rock (granite mountains) and liquid regions (volcanic magma or water of the oceans) on the Earth These waves are like sound waves (compression waves) Travel the fastest

Write in notebook Write in notebook Secondary (S) waves only travel through rock Move twice as slow as P waves Moves at right angles to the direction of travel (transverse waves)

Write in notebook Surface wave Motion is felt along the ground and Earth’s surface. Appear like waves or ripples of water that travel across a lake

Types of earthquake waves Types Of Earthquake Waves

Questions What are two parts of the mantle? Upper mantle and lower mantle What is the lithosphere? Rocky outer parts of the planet. Makes up the upper mantle and the crust How thick is the mantle? It is the thickest layer of the earth, 1800 miles thick Is the crust solid, liquid, or gas? Mostly solid What is the asthenosphere made of? Rocks that can flow like a liquid What is the crust’s temperature? degrees F

Outer Core Made up of liquid iron and nickel, or molten metal 7232 degrees F 1400 miles thick Causes pieces of the crust to move It is liquid More dense than crust and mantle Less dense than inner core

Inner Core Inner Core Made up of solid iron and nickel Densest layer 9032 degrees F, just as hot as the sun! It’s not liquid. The pressure causes the iron and nickel to solidify

Inner Core The pressure comes from the weight of the entire world Where the magnetic field lies This protects us from deadly solar winds from the sun

Inner Core

Questions Which part of the core is solid and which part is liquid? Outer core is liquid, inner core is solid What are the inner core and outer core made of? Nickel and iron What is the outer core’s temperature? 7232 degrees F What is the inner core’s temperature? 9032 degrees F