Earth’s Crust

1
Earths Crust
2
Convection currents
3

• 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.

4

• Ocean floor spreading theory that hot less
  dense material below Earths 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/n
  sta/divergent-boundary-oceanic.gif
• Convection current unequal distribution of heat
  in the mantel causes a net movement in a circular
  motion.

5
(No Transcript)
6

• The Earths CRUST is the outer most part of the
  Earths surface.
• Average 32 km thick
• Thickest point 70 km (in mountains)
• Thinnest point 8 km (under ocean)

7

• Plate tectonic theory that Earths crust and
  part of the upper mantle are broken into sections
  called plates.
• Lithosphere all of the earths crust and part
  of the upper mantle.
• http//www.allaboutspace.com/subjects/astronomy/pl
  anets/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.

8

• l

9
(No Transcript)
10

• Deformation The breaking, tilting, and folding
  of crustal rock due to crustal movement. (three
  types of forces)
• Compression squeezing of earths crust that
  compacts the rock. Convergent boundary
• 2. Tension is the pulling apart of the earths
  crust. Divergent boundary.
• 3. Shearing pushes rocks side by side in
  opposite directions. Transform boundary.

11
Convergent boundary
Divergent boundary
Transformation boundary
12
(No Transcript)
13
Rift valley
subduction
14

• FAULTS
• Normal Fault fault caused by tension stress
  that moves the hanging wall down relative to the
  foot wall.

15

• Reverse Fault fault caused by compression
  forces where the hanging wall will move up
  relative to the foot wall.

16
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.
17
Thrust Fault is formed when compression causes
the hanging wall to slide over the foot wall.
(almost horizontal movement)
18

• Facts about folds/faults.
• increased temp. s fold
• decreased temp s fault
• increased pressure s fold
• decreased pressure s fault
• rock type brittle s fault
• rock type ductile s fold
• time greater the time s fold
• time less time s fault

19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23

• Fault block mountain is a mountain created by
  blocks of rock uplifted by normal faults.

24

• Rift Valley are valleys created when a block of
  land between two normal faults slide downward.

25

• End of chapter 10

26

• Folds are bends in rocks without breaking
• folds have two parts
• Anticline upward part of fold
• syncline downward part of fold

Anticline
27
(No Transcript)
28

• Plateau is a large area of flat land that is
  raised high above sea level. Usually bordered by
  cliffs or mountains.

29

• Domes is the uprising area caused by magma

30

• Floating crust -

less dense
more dense
31

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