Planet Earth

1
Planet Earth
2
Earths Formation

• The earth formed by accretion of dust and small
  objects in the early solar system.
• Heat from collisions
• Melt and reform
• Earth rocks are compared to meteorites and moon
  rocks.

orbital motion
collision
different orbit
3
Layers in the Earth

• Heating the earth caused the heavy metals to sink
  and lighter minerals to rise.

inner core
outer core
mantle
crust
4
Seismic Waves

• Earthquakes near the surface create vibrations.
• P waves compress
• S waves shake, slower
• Waves can be measured at surface points far away.
• Interior information

5
Core

• The earths core consists of iron and other
  metals.
• 3500 km radius
• Radioactivity keeps it hot.
• Temperature to 6500 K
• Liquid metal outer core
• Density keeps part solid.
• Solid within 1200 km
• Pressure over 1 million atmospheres

U Colorado
6
Mantle

• Lighter minerals congregated above the core.
• Silicates silicon, aluminum, magnesium, oxygen
• Iron, too
• The mantle is solid, but plastic.
• Slow movement, like putty under pressure.

crust
mantle
convection
outer core
7
Crust

• The crust is the cool, hard surface of the
  mantle.
• ocean - more dense, basalt rock
• continents - less dense, granite rock
• The crust is very thin 10 km out of 6400 km
  radius.

continent
ocean floor
crust
mantle
outer core
8
Plate Tectonics

• Motion in the mantle causes the crust to split.
• Earthquakes, mountains, volcanoes
• Plate tectonics causes continents to move over
  millions of years.

overriding plate
crust
mantle
descending plate
outer core
ZME Science
9
Hot Plumes

• The heat from the outer core causes molten rock
  to rise through the mantle.
• Surface rises
• The dense rock causes gravity to be very slightly
  higher.

bulge at the surface
crust
mantle
plume
outer core
10
Volcanism

• Plumes that push material to the surface form
  volcanoes.
• Gases and minerals in volcanoes tell us about the
  earths mantle.

volcano
crust
mantle
plume
outer core