Inside the Earth

1
Inside the Earth
2
Earths Interior

• Earths interior is divided into layers the
  crust, mantle, inner and outer core, based on
  composition. Although the Earths crust seem
  stable, the extreme heat of the Earths interior
  causes changes that slowly reshape the surface.

3
Earths Interior

• The three main layers of Earth are the crust, the
  mantle, and the core (inner and outer core
  compositionally similar).

4
The Crust

• Oceanic Crust
• crust beneath the oceans
• consists mainly of dense rock (basalt - dark in
  color)
• 5-8 km thick
• Continental Crust
• crust that forms the continents
• consist mainly of less dense rock (granite -
  lighter in color)
• 30 km average thickness

5
Crust to Mantle

• The upper part of the mantle and the crust
  together form a rigid layer called the
  lithosphere.
• Lithos is greek for stone, 100 km thick
• made of pieces called tectonic plates

6
Crust to Mantle

• The asthenosphere is a soft layer of the
  mantle of which pieces of the lithosphere move
• asthenes is Greek for soft or weak
• material is like warm tar and can flow slowly
• The rigid crust and
  lithosphere float on
  the hot, plastic
  material of
  the
  asthenosphere.

7
The Mantle

• layer of rock between crust
  and core
• 2900km thick, 67 of Earths mass
• Composition - silicon, oxygen, iron and
  magnesium
• physical conditions in mantle change because
  pressure and temperature increase with depth
• temp ranges from 870 ºC to 2,200ºC

8
Convection Currents inside the Mantle

• Hot columns of mantle material rise slowly
  through the asthenosphere

9
The Core

• The core is made mostly of the metals iron and
  nickel.
• It consists of two partsa liquid outer core and
  a solid inner core.

10
The Core

• Innermost layer of the Earth
• 6800 km in diameter (3,400 km from outside edge
  of core to center of core)
• 1/3 of Earths mass, 15 of its volume
• Temperature ranges form 2,000 ºC to 5,000 Cº

11
The Outer Core

• layer of molten metal (iron and nickel) beneath
  the mantle
• surrounds the inner core
• 2,200 km thick

12
The Inner Core

• dense ball of solid metal (iron and nickel)
• extreme pressure from layers above
• 1200 km, from outside edge of inner core to
  center

13
Earths Magnetic Field

• Currents in the liquid outer core spin at
  different speeds than do the solid inner core
• Scientists think that differences in the spinning
  speed of the inner and outer core create Earths
  magnetic field.

14
Earths Magnetic Field

• The earth acts as a giant bar magnet
• Earths magnetic fields have reversed more than
  177 times in the last 85 million years