Download Forces in the Crust Day1

AIM: Describe the types of stress and the land features
(faults,uplift,folds) that result from forces (stress) in the
Earth’s crust?
OBJ: Given notes and activity sheet SWBAT describe the
types of stress and the land features (faults, uplift, folds)
that result from forces (stress) in the Earth’s crust with 70%
accuracy
DN: Distribute Tectonics Activity Sheet
ACT: Introduction to stress, types of stress, fault, kinds of
faults and land features (uplift, folding).
Text, read p. 44-50.
HW: Work on Tectonics
Tectonics Exam, February 12.
Activity Sheet;
Movement of Earth’s plates creates enormous
forces (stress) that pull or squeeze the rocks in
the crust.
Stress: a force that acts on rock to change its
shape or volume.
Volume: the amount of space the rock takes
up.
The stress transfers energy to the rock causing
the rock to bend/stretch. But beyond a certain
limit, the rock will break.
Types of Stress (Crust)
Occurs over millions of years to change shape
and volume of rock.
Tension: move apart, stretch rock, divergent
motion
Compression: come together, squeeze rock,
convergent motion
Shearing: to move in opposite directions, slip &
slide past each other, side by side motion
Fault: a break in rock along which movement
occurs (= earthquake). Most faults occur along
plate boundaries.
Kinds of Faults
Normal Fault: caused by tensional forces where
plates pull apart (diverge) forming a step-like
structure.
Reverse Fault: caused by compressional forces
where plates come (squeeze) together (converge)
forming a “roof shingles” structure.
Strike-Slip/Transform Faults: caused by shearing
forces where plates move past each other in
opposite directions.
Changing Earth’s Surface
Over millions of years, the forces of plate
movement can change a flat plain into folded
mountains, fault-block mountains and plateaus.
Folded Mountains: site of collision between
two plates.
Fold: bends in rock formed by compressional
forces that shorten and thicken part of the crust.
Anticline: a fold in rock that bends upward into
an arch.
Syncline: a fold in rock that bends downward to
form a valley.
Fault-Block Mountains: where two plates move apart tensional
forces can create parallel normal faults. As the plates move
apart, the block in between moves upward forming a fault-block
mountain.
Horst
Graben
Graben
Graben
Horst
Horst
Graben
Plateaus: a large area of flat land elevated
high above sea level formed by uplifting forces
in Earth’s crust.