Structure of the Earth Objective: describe the structure of the Earth
Nebular Hypothesis showing Earth’s Formation • Interstellar dust & gas begin to condense. • The material converges, spinning faster & growing hotter. A cooler disk of ice & rock is surrounded by hotter gas. • As fusion occurs, a star forms & planetesimals form, attracting more material as they orbit. • Over time, the material all from the original cloud becomes a solar system.
In the center of the Earth is the Inner Core. • The Inner Core is made of solid iron and nickel. • The Inner Core goes from 5150 – 6371 km below ground
The Inner Core is surrounded by the Outer Core. • The Outer Core is made of liquid iron and nickel • The Outer Core goes from 2890-5150 km below ground • The Outer Core’s material spins around the solid inner core, this creates the Earth’s magnetic field
Around the Outer Core is the Mantle • The Mantle is divided into two major layers, the Lower and Upper Mantle • The Lower Mantle is made of solid rock, but very high pressure inside the Earth makes it act like a liquid. • The Mantle goes from 65- 2890 km below ground
The Upper Mantle is divided into two layers, the Asthenosphere and the Lithosphere.
The Asthenosphere is closer to the Earth’s Core. • It is made of “slush-like” rock- it can act like a solid or a liquid
The Lithosphere is closer to the Earth’s Surface. • It contains both the uppermost part of the Mantle and Earth’s Crust • It is made of rigid (solid) rock
Above the Mantle is the Crust • The Crust is made of light, solid rocks. • It is divided into the oceanic (thinnner; avg=7km/ younger=180myo or less) & continental Crust (thicker; avg=40km/older= some over 4byo.) • The Crust goes from the surface of the Earth to 65 km below ground.
Pressure & Temperature increases as you get farther inside the Earth. • The Crust has very low pressure. • The Inner Core has very high pressure. Pressure Increases
How do we know all this? Earth’s Layers: • Studies of p & s waves through Earth helped scientists identify the boundaries of Earth’s layers & determine that the outer core is a liquid. Earth’s Composition: • Scientists studied seismic data, rock samples from the crust & mantle, meteorites, & high-pressure experiments on Earth materials.