FOLDS, FAULTS, AND JOINTS Flashcards
(26 cards)
are bends or wavelike structures in rock
layers caused by compressional forces. They
occur when rocks behave plastically (ductile
deformation) and do not break.
FOLDS
TYPES OF FOLDS
SYMMETRICAL FOLD
ASYMMETRICAL FOLD
OVERFOLD
RECUMBENT FOLD
Both limbs of the fold have
equal angles relative to the
axial plane, indicating
uniform compressional
forces from both sides.
SYMMETRICAL FOLD
One limb is tilted beyond the
vertical, causing the layers to
overlap, often due to intense
compressional forces.
OVERFOLD
The limbs exhibit
different angles,
suggesting unequal
compressional forces
during formation.
ASYMMETRICAL FOLD:
The axial plane is nearly
horizontal, resulting in a
fold lying on its side,
typically found in regions
with significant tectonic
activity, such as mountain
belts formed by plate
collisions.
RECUMBENT FOLD
are fractures in rocks along which
movement has occurred. They result from
brittle deformation and can be classified
based on the direction of movement.
FAULTS
3 TYPES OF FAULTS
NORMAL FAULT
REVERSE FAULT
STRIKE-SLIP FAULT
Occur due to tensional
forces; the hanging wall
moves down relative to the
footwall
NORMAL FAULT
typically associated
with divergent plate
boundaries.
NORMAL FAULT
Form under
compressional forces;
the hanging wall moves
up relative to the
footwall.
REVERSE (THRUST) FAULTS
often associated with
convergent plate
boundaries.
REVERSE (THRUST) FAULTS
is a
geological fault where the
movement of tectonic plates
occurs predominantly
horizontally, parallel to the
fault plane, in opposite
directions, typically due to
horizontal shearing forces.
STRIKE-SLIP FAULT
are primarily
associated with
transform plate
boundaries
STRIKE-SLIP FAULT
are fractures in rocks where there is little to no
movement.
JOINTS
joints form due to
cooling, unloading, or
tectonic stress.
unlike faults, _____ do not show
significant displacement. They can occur in parallel
sets and often influence weathering, erosion, and fluid
movement in rocks.
joints
TYPES OF JOINTS
Tectonic Joints:
Extension Joints:
Hydraulic Joints:
Exfoliation Joints:
Unloading Joints:
Cooling Joints:
Formed by tectonic stresses and movements in the Earth’s crust.
Tectonic Joints:
Form when rocks are subjected to tensile stress, pulling the rock apart,
leading to the opening of cracks.
Extension Joints:
Formed by the action of water, such as erosion or pressure.
Hydraulic Joints:
Formed by the peeling off of rock layers due to pressure release.
Exfoliation Joints:
Formed by the release of pressure on rocks, such as when overlying rocks
are removed.
Unloading Joints:
Formed by the cooling and contraction of rocks, such as columnar jointing.
Cooling Joints:
