Unit 1: Introduction to Earth Science part 3 Segregation/Formation Of Earth’s Layers

Origin of the earth It was thought that Earth was not always layered as it is today. Some scientists suggest that Earth was somewhat like the moon billions of years ago

Why does earth have layers?

Why does earth have layers? Thanks to nature (i.e. heat and gravity) Sources: Radioactive Decay Particle Collisions Residual Heat Related to density

Why does earth have layers? Heat: from particle collisions and radioactive elements produced melting of the interior. Denser material sank to the Earth’s center (due to gravitational forces) lighter materials floated upwards. This process is often referred to as differentiation or segregation. *still occurring today (smaller scale)

Why does earth have layers? Gases are released from Earth’s interior through volcanoes. This segregation/differentiation caused the geosphere (Solid Earth) to developed layers that have different properties.

Differentiation Video

Layers of the earth Both the inner and outer core are made up of Nickel and iron (due to segregation), but they have different States of Matter. Why would they be in different states? One solid, one liquid Which would be solid; the inner or outer core? Why?

Layering of Earth pg. 22, 476

State: Thin, rocky outer skin Crust Lithosphere State: Thin, rocky outer skin Composition: felsic rock - granite is dominant rock Density: 2.7 g/cm3 (mostly low density rock) Temperature: increases with depth 400 C *Roughly 100km think (varies depending on ocean or continental) -

Plate tectonics

Temperature: increases with depth to 3500 C. Asthenosphere (upper mantle) Mantle State: Mainly solid, very strong but can flow (like silly putty or an eatmore bar) Composition: Dominant rock is ultramafic - Dominant rock type is called ‘peridotite” Density: 3.3 g/cm3 (increases in density as it goes deeper-segregation) Temperature: increases with depth to 3500 C. *Is 2900 km thick – The thickest layer!

Composition: iron and a small amount of nickel Density: 11 g/cm3 Outer Core State: liquid Composition: iron and a small amount of nickel Density: 11 g/cm3 Temperature: > 6700 C * 2270 km thick - convection currents exist within and contributes to origin of magnetic field

*Hotter, denser and stronger that outer core **State: solid Inner Core *Hotter, denser and stronger that outer core **State: solid Radius = 1216 km

Temperature and Density Increases with Depth Density inside Earth increases as depth inside Earth increases. Temperature inside Earth increases at a rate of approximately 35 degrees celcius per kilometer. This is referred to as the Geothermal Gradient.

Earth is a Dynamic Planet It changes slowly over millions of years (erosion of a mountain) But it can also have dramatic quick changes (volcanic eruptions and earthquakes)

Hydrosphere Biosphere Geosphere Atmosphere

Which layer do you think developed 1st? 2nd? 3rd?

Order of development Geosphere  hydrosphere  atmosphere biosphere Hydrosphere and atmosphere formed from early “outgassing”, where molten material cooled and released dissolved gases into the atmosphere (N2, H2O vapor, CO2, Ar)

The earth is a complex set of interacting systems Each sphere influences one another and effects our daily lives

The earth is a complex set of interacting systems Ex. Water cycle Ex. Volcanic eruption How does each illustrate interactions among Earth’s spheres?

All 4 spheres?

All 4 Spheres

All 4 Spheres Shoreline