Content Outline for Teaching - Potosi School District - Home

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Section 1
Content Outline
for Teaching
Earth’s Moving Plates
Forces Shaping Earth
Underlined words and
phrases are to be filled
in by students on the
Note-taking Worksheet.
A. Geologists use earthquakes and surface rocks to indirectly observe Earth’s interior.
1. Seismic waves change speed and direction depending on the density and
material they travel through.
2. Forces bring rocks formed deep within Earth to the surface.
3. Evidence suggests that Earth is formed of different materials in layers.
B. Earth has four layers.
1. Inner core—dense iron core; very hot and dense
2. Outer core—molten metal above the inner core
3. Solid layer that flows slowly like putty is the mantle.
4. Outermost layer is the crust.
C. Earth’s structure—theories based on physical properties of density, temperature,
and pressure that change with depth
D. Earth’s moving plates are sections of the lithosphere, the rigid upper part of the
mantle and crust.
E. Plate boundaries are edges where plates meet.
1. Tension can pull plates apart,resulting in new lithosphere forming in the gaps.
2. Colliding plates could cause mountains to form as rock crumbles and folds.
3. Subduction occurs when a denser plate sinks underneath a less dense plate.
4. Shearing causes faults and earthquakes as two plates slide past each other.
F. Plate movement theory—convection in the mantle circulates material and
moves plates.
1. Ridge-push at mid-ocean ridges causes plates to slide down the slope.
2. Slab-pull happens as plates move away from mid-ocean ridges and become
denser.
Discussion Question
Name Earth’s four main layers. inner core, outer core, mantle, and crust
Forces Shaping Earth 29