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Forces Shaping Earth

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Forces Shaping Earth Notes Mrs. Seay 6th Grade Science Geologists use earthquakes and surface rocks to indirectly observe Earth s interior 1. Seismic waves change ... – PowerPoint PPT presentation

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Title: Forces Shaping Earth


1
Forces Shaping Earth
  • Notes
  • Mrs. Seay
  • 6th Grade Science

2
  • Geologists use earthquakes and surface rocks to
    indirectly observe Earths interior

3
  • 1. Seismic waves change speed and direction
    depending on the density and material they travel
    through.

4
  • 2. Forces bring rocks formed deep within Earth
    to the surface.

5
  • 3. Evidence suggests that Earth is formed of
    different materials in layers.

6
  • B. Earth has four layers.

7
  • Inner coredense iron core very hot and dense.

8
  • Outer coremolten metal above the inner core

9
  • Solid layer that flows slowly like putty is the
    mantle.

10
  • Outermost layer is the crust.

11
  • C. Earths structuretheories based on physical
    properties of density, temperature, and pressure
    that change with depth.

12
  • Earths moving plates are sections of the
    lithosphere, the rigid upper part of the mantle
    and crust.

13
  • Plate boundaries are edges where plates meet.

14
  • Tension can pull plates apart, resulting in new
    lithosphere forming in the gaps.

15
  • Colliding plates could cause mountains to form as
    rock crumbles and folds.

16
  • Subduction occurs when a denser plate sinks
    underneath a less dense plate.

17
  • Shearing causes faults and earthquakes as two
    plates slide past each other.

18
  • Plate movement theoryconvection in the mantle
    circulates material and moves plates.

19
  • Ridge-push at mid ocean ridges causes plates to
    slide down the slope.

20
  • Slab-pull happens as plates move away from
    mid-ocean ridges and become denser.

21
  • Mountains form in different ways.

22
  • Fault-block mountains form from huge tilted
    blocks of rock separated from surrounding rock by
    large faults.

23
  • Folded mountains form by compression forces
    folding rock layers.

24
  • Upwarped mountainsforces push up Earths crust
    and allow the sedimentary rock to erode, leaving
    igneous or metamorphic rock.

25
  • Over time, layers of lava can form a cone-shaped
    volcanic mountain.

26
  • Hot spots formed by plumes of magma in the mantle
    can cause underwater volcanic mountains.

27
  • Isostacy principle in dicates Earths crust and
    lithosphere float on the upper mantle.

28
  • Earths crust is thicker under mountains.

29
  • When mountains erode, the crust rises because the
    weight has been removed.
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