Earth�s Crust by 815MfXx

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									Earth’s Crust
Convection
currents
Continental drift – idea that continents
 have moved slowly to their current
 positions due to convection currents
 in the mantel.
Pangea – the idea that the all land
 masses on earth were once a single
 large land mass.
Ocean floor spreading – theory that
 hot less dense material below Earth’s
 crust rises toward the surface at the
 mid-ocean ridges. Then, it flows
 sideways, carrying the seafloor away
 from the ridge in both directions.
 http://geology.com/nsta/divergent-boundary-oceanic.gif




Convection current – unequal
 distribution of heat in the mantel
 causes a net movement in a circular
 motion.
The Earth’s CRUST is the outer most part of
   the Earth’s surface.
• Average 32 km thick
• Thickest point 70 km (in mountains)
• Thinnest point 8 km (under ocean)
Plate tectonic – theory that Earth’s crust and part
  of the upper mantle are broken into sections
  called plates.

Lithosphere – all of the earth’s crust and part of
  the upper mantle.
http://www.allaboutspace.com/subjects/astronom
  y/planets/earth/Inside.shtml
Asthenosphere – plastic like layer below the
  lithosphere. The ridged plates of the lithosphere
  “float” on the more plastic layer called the
  asthenosphere.
l
Deformation – The breaking, tilting, and
   folding of crustal rock due to crustal
   movement. (three types of forces)
     1. Compression – squeezing of earth’s
        crust that compacts the rock.
        Convergent boundary
     2. Tension – is the pulling apart of the
        earth’s crust. Divergent boundary.
     3. Shearing – pushes rocks side by
        side in opposite directions.
        Transform boundary.
Convergent boundary




 Divergent boundary




   Transformation boundary
Rift valley




subduction
FAULTS
Normal Fault – fault caused by tension
 stress that moves the hanging wall down
 relative to the foot wall.
Reverse Fault – fault caused by
 compression forces where the hanging
 wall will move up relative to the foot wall.
In Lateral (strike-slip) faulting, the two blocks
move either to the left or to the right relative to
one another. Strike-slip faults are associated with
crustal shear.
Thrust Fault – is formed when compression
causes the hanging wall to slide over the foot
wall. (almost horizontal movement)
Facts about folds/faults.
1. increased temp. =‘s fold
2. decreased temp =‘s fault
3. increased pressure =‘s fold
4. decreased pressure =‘s fault
5. rock type – brittle =‘s fault
6. rock type – ductile =‘s fold
7. time – greater the time =‘s fold
8. time – less time =‘s fault
Fault block mountain is a mountain created by
blocks of rock uplifted by normal faults.
Rift Valley are valleys created when a block of
land between two normal faults slide downward.
• End of chapter 10
Folds – are bends in rocks without breaking
     • folds have two parts
     1. Anticline – upward part of fold
     2. syncline – downward part of fold




                          Anticline
Plateau – is a large area of flat land that is raised
high above sea level. Usually bordered by cliffs or
mountains.
Domes – is the uprising area caused by magma
Floating crust -




          more dense   less dense
•A balance exist between the downward force of
the crust and the upward force of the mantle
called ISOSTASY.

								
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