Download Chapter 4 lesson 1

Lesson 4.1: Forces in Earth’s Crust
Stress
Study Guide
A force that acts on rock to change its shape or volume
Key Idea: There are three kinds of stress that can occur in the crust. When stress builds up in rock, the rock
breaks and creates a fault. This usually happens at a plate boundary.
Divergent Boundary
A plate boundary where two plates
move away from each other
Tension
Stress that pulls and stretches rock so
that it becomes thinner in the middle
Convergent Boundary
A plate boundary where two plates
move toward each other
Transform Boundary
A plate boundary where two plates
move past each other in opposite
directions
Compression
Stress that squeezes rock together
until it folds or breaks
Normal Fault
Reverse Fault
A type of fault where the hanging wall
slides downward; caused by tension in
the crust
A type of fault where the hanging wall
slips upward; caused by compression
in the crust
Shearing
Stress that pushes masses of rock in
opposite directions in a sideways
movement
Strike-Slip Fault
A type of fault in which rocks on either
side move past each other in opposite
directions with little up or down
motion
Key Idea: Forces of plate movement can change a flat plain into features, such as anticlines and synclines,
folded mountains, fault –block mountains, and plateaus.
Compression can fold Earth’s crust.
 These folds are called anticlines and synclines.
o Anticlines-upward folds
o Synclines- downward V shaped folds
 Collision of plates causes compression.
o Compression from collision can form folded mountains
 Examples: Himalayas and Alps
Tension can form fault-block mountains and valleys.
 Two normal faults cause the hanging walls to fall downward creating valleys.
 The block in between now stands higher, creating fault-block mountains.
Forces in Earth’s crust can also push up large, flat blocks of rock.
 Plateau- A large landform that has a high elevation and a more or less flat surface