Download Earth as a system The rock cycle Earth`s internal structure

1/5/2011
Earth as a system
• The Earth system is also powered from the
Earth’s interior
• Heat remaining from the formation and
• Heat that is continuously generated by
radioactive decay powers the internal
processes that
• Produce volcanoes, earthquakes, and
mountains
• i.e., The rock cycle
The rock cycle
The rock cycle: part of
the Earth system
• The loop that involves the processes by
which one rock changes to another
• Illustrates the various processes and
paths as Earth materials change both on
the surface and inside the Earth
Earth’s internal structure
• Earth’s internal layers can be defined by
• Chemical composition
• Physical properties
• Layers defined by composition
• Crust
• Mantle
• Core
Earth’s internal structure
• Four main layers of Earth are based on physical
properties and mechanical strength
• Lithosphere: “sphere of rock”, 5 – 250 km. thick. cool,
rigid and brittle. The location of all earthquakes.
• Asthenosphere: “weak sphere” 660 km. thick
plastic region where rock begins to melt
• Mesosphere: “middle sphere” 2240 km thick. Pressure
strengthens the molten rock, still hot but also brittle
• Core: Mostly iron and nickel, Outer core 2270 km thick.
Liquid movement generates magnetic field. Inner core
1216 km behaves like a solid and is as hot as the surface
of the sun.
Created with Print2PDF. To remove this line, buy a license at: http://www.binarynow.com/
1
1/5/2011
Dynamic Earth
Dynamic Earth
• The theory of plate tectonics
• The theory of plate tectonics
• Involves understanding the workings of our
dynamic (always changing) planet
• It began in the early part of the twentieth
century with a proposal called continental
drift – the idea that continents moved about
the face of the planet
• A theory, called plate tectonics, has now
emerged that provides geologists with the
first comprehensive model of Earth’s
internal workings
• Plate boundaries
• All major interactions among individual
plates occurs along their boundaries
Dynamic Earth
Divergent Boundary
• Plate boundaries
• Divergent boundary – two plates move apart,
resulting in upwelling of material from the
mantle to create new seafloor
• Convergent boundary – two plates move
together with subduction of oceanic plates or
collision of two continental plates.
• Transform boundaries - located where plates
grind past each other without either generating
new lithosphere or consuming old lithosphere
•
•
•
•
•
•
Mid-Ocean Ridge
Motion: Away from one another
Process: new seafloor is created
Appears like a scar on the map
Earthquakes: yes
Volcanics: yes
Convergent Boundary
•
•
•
•
•
Motion: Towards one another
Common name: Subduction zone
Ocean plate always subducts.
Earthquakes: yes
Volcanics: yes
Transform Boundaries
•
•
•
•
•
•
•
Motion: Slide past one another
Apparent motion
Process: Strike-Slip
Appears like offsets in the Mid-Ocean Ridge
Most visible for us is the San Andreas Fault
Earthquakes: yes
Volcanics: no
Created with Print2PDF. To remove this line, buy a license at: http://www.binarynow.com/
2