On Monday and Tuesday…  We found the density of liquids and rocks.  We learned that denser materials sink, and lighter materials float.  We learned that granite is lighter than basalt and that iron is denser than both.

Density and the Inner Earth  DENSITY = MASS / VOLUME  In other words: How much stuff is there in a certain amount of space.  We also learned that the densest liquids sink to the bottom, and the lightest liquids float.  The same is true with the rock inside the Earth!

Which plate would be subducted?  Oceanic plate made of basalt collides with continental plate made of granite  Basalt has a higher density than granite.  The oceanic plate will be subducted  Ocean-Ocean?  Both could be subducted because both are dense. However, only one is actually subducted. Trench is formed, volcanic islands.  Ocean-Continent?  Oceanic plate is subducted because it is more dense. Trench is formed, land volcanoes.  Continent-Continent?  Neither is subducted because both are less dense than the magma beneath them. Mountain formation, no volcanoes.

How do you think density affects the composition of the Earth?

The Earth has 4 major layers  Crust  Mantle  Inner Core  Outer Core

The Crust OOuter layer 55-100 km thick 22 types of crust OOceanic (very dense, made of basalt) CContinental (less dense, made of granite) IIf the Earth were a basketball, the crust would be a sheet of paper.

Oceanic and Continental Crust

The Mantle  Middle, very thick layer  The largest section of the Earth, both in mass and volume.  Made of magma very much likes comes out of volcanoes as lava  Has an upper and a lower part. Upper is PLASTIC, lower is RIGID.  The upper mantle has CONVECTION CURRENTS. The magma flows and cycles.

The Outer Core  Made mostly of liquid iron  1/3 of the earth’s mass  Hotter than the surface of the sun  Contains radioactive material that helps keel the Earth warm.

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. The inner core is a solid. The inner core gives the Earth it’s magnetic field, which protects us from the sun.

Pair and Share  Turn to the person next to you and tell them one fact about one layer of the Earth.  Then, they tell you another fact about another layer of the Earth.  Do this for all 4 layers.

Convection in the Mantle

Oil and Pepper Demonstration  Make a hypothesis about what will happen when we heat the oil and pepper. (If-Then format)  Observe the movement of the pepper  Collect Data on what happened. What do you notice?  Analyze your data. Why did that happen?

What is Convection?  Convection is the transfer of heat within a liquid that creates movement called convection currents.  When a substance is heated, it expands.  As it expands, it’s density decreases and it becomes lighter. It rises  When a substance cools, it contracts  As it contracts, it’s density decrease and it becomes lighter. It sinks.

Convection in the Mantle  Convection in the mantle causes Divergent Plate Boundaries, by breaking a plate apart and then forcing the two parts in opposite directions.  Continents are carried by the convection currents in the mantle

Exit Slip  1) Define density (either the equation or in your own words)  2) List the 4 layers of the Earth and give one fact about each of them.