Geology Thinking Sheet 12117 or 12417 What is

Geology Thinking Sheet 12/1/17 or 12/4/17 What is the chemical composition of these items: Water Air Human Body (HINT: What atoms are in these items? )

Vocabulary! Describes the way a substance looks or interacts with other substances Physical Properties Lithosphere Asthenosphere Mesosphere Outer Core Inner Core

Physical Properties These layers are separated based on how they interact with each other.

How the Earth is Separated Scientists can separate the layers of the earth in two different ways. 1. The group of scientists that study what the layers are made of look at CHEMICAL COMPOSITION 2. The group of scientists that study how the layers interact look at PHYSICAL PROPERTIES

Chemical Composition First we will discuss chemical composition layers. These layers separated based on the kinds of atoms and molecules in each layer.

Chemical Composition Crust Mantle Core

Crust �The crust is the OUTER MOST layer of the Earth. �It is composed mostly of a molecule called SILICA. Silica has a low density. 14 8 Si O 28. 0855 15. 9994

Crust

Evidence: Crust Analyzing the chemicals found in rocks that form near or on the surface Granite Obsidian 72% Si. O 2 72. 5% Si. O 2

Mantle �Thick, hot layer in the middle of the earth �The mantle is composed of silica as well, but there is also a lot more magnesium and iron in the mantle than in the crust 14 8 12 26 Si O Mg Fe 28. 0855 15. 9994 24. 3050 55. 0855

Evidence: Mantle Analyzing rocks that come from the upper mantle. These are called peridotite xenoliths.

These mantle rocks have VERY high melting points, allowing them to remain solid, even under the high temperature and pressure of the mantle.

Evidence: Mantle These rocks can flow through the mantle like ice in a pitcher of water. When rocks from the mantle hitch a ride to the surface we can analyze their composition.

Evidence: Mantle These rocks are formed in Earth’s upper mantle. Peridotite Eclogite Less than 45% Si. O 4 High in Magnesium Less than 50% Si. O 2 High in Magnesium and Iron

Chemical Composition Sort the cards into two groups: • Crustal Rocks (made of mostly Si and O) • Mantle Rocks (still has Si and O, but also includes Mg or/and Fe)

Core �This is the innermost portion of the Earth. �Evidence suggests that the core is composed mostly of iron and nickel 26 28 Fe Ni 55. 845 58. 6934

Evidence: Core Earth’s Magnetic Field Magnetic fields are produced by moving electric charges. Earth’s core is believed to be highly conductive molten iron. That along with the rotation of the earth allows a magnetic field to surround our Earth.

Evidence: Core �The composition of meteorites (called Chondrites) tells us there is a lot of iron and nickel in the center of the earth.

These two small meteorites probably came from the core and mantle of the same large asteroid. The pallasite came from the asteroid's core-mantle boundary, where olivine from the mantle mixed with iron-nickel metal from the core.

Scientists have found that this is the composition of meteorites, which can lead us to assume that our Earth has the same composition. A lot of the Silicon and Oxygen are in our crust, and much of the Magnesium is in the mantle. This leads us to assume that the Iron (not found in abundance on the surface), must be in the core.

Additional Evidence Seismic studies show that earthquake waves change velocity as they move through the earth. This is evidence that each layer is composed of different materials.

Physical Properties Lithosphere Asthenosphere Mesosphere Outer Core Inner Core

Lithosphere �The lithosphere is a solid outer layer of the earth. (Litho = Rock) �It is made of Earth’s crust and the upper, solid part of the Mantle

Asthenosphere �The asthenosphere is a HOT, semi-solid layer just below the lithosphere. (Astheno = Weak) �It is made of Earth’s upper mantle. Scientists describe it as “plastic-like”

Asthenosphere Evidence: Heat from volcanic lava comes from near the asthenosphere.

Physical Properties Important Interaction: • The SOLID Lithosphere floats on top of the SEMI-SOLID Asthenosphere…causing plate movement! Lithosphere (rigid solid) Asthenosphere (capable of flow)

Mesosphere �It is made of Earth’s middle and lower mantle. Scientists believe this layer is a fluid, semi-solid (like molasses or hot toothpaste)

Mesosphere Evidence: • Earthquake waves increase their velocity in this layer.

Outer Core �It is made of Earth’s upper core. �The outer core is made of liquid iron and nickel. (Liquid because of the high temperature) �This liquid metal is responsible for our magnetic field

Physical Properties Important Interaction: • Heat from the Mesosphere and Outer Core move magma upward into the Asthenosphere, where the temperature cools and the magma sinks. Asthenosphere Mesosphere Outer Core

Inner Core �The inner core is made of solid iron and nickel. �Density tells us that those heavy elements sink. �Pressure tells us that the center of the earth is so squished that the iron and nickel are in a solid state of matter.

Additional Evidence Again, Earthquakes Reveal the Layered Earth P-wave (Primary) can travel through solids (like the lithosphere and asthenosphere) and liquids (like the outer core). S-waves (Secondary) can only travel through solids (lithosphere and asthenosphere)