Density of rocks 1) Find the mass of each rock sample on the electric balance. Record measurement in data table (g). 2)Pour 50 mL of water from beaker into the graduated cylinder. Use dropper to get the exact amount of 50 mL. 3) CAREFULLY drop rock #1 into graduated cylinder and determine volume of rock in mL using water displacement method. 4) Calculate volume or rock: (final volume – initial volume) Repeat step 4 with other rocks. Record data (mL) 5) Calculate the density of each rock Density= mass/volume. Use the unit for density (g/mL), record in data table.

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.

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!

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.

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.