Earth Science Quiz 2 Q2 Flashcards
Rocks change their shape and volume when they are subjected to ________.
stress
These are caused by forces that are exerted on the edges or interior of a material.
Stress
______ constantly exerts downward stress on all rocks.
Gravity
Temperature changes cause _________ __________ and _________ that causes fractures.
thermal expansion, contraction
Wetting and drying can induce or enhance __________.
fractures
HORIZONTAL plate movement exerts:
lateral and vertical stress
What is stress synonymous to?
pressure
_______ is the pressure that the rocks experience due to different forces.
stress
Two types of of stress:
Uniform & Differential Stress
Type of Stress. Forces act EQUALLY in all directions. It is confining.
Uniform Stress
Type of Stress. Opposite in direction, equal in magnitude.
Uniform Stress
Type of Stress. It causes deformation and plate tectonic forces. There is DIRECT pressure.
Differential Stress
Type of Stress. It is the difference between the greatest and least compressive stress and experienced by an object. The difference in stress is responsible for the DEFORMED nature of rocks.
Differential Stress
Examples of differential stress:
Tensional, Compressional and Shear stress
Differential Stress. Rocks are PULLED APART that result to lengthening and break apart.
- Stretches Rock (Parang clay)
Tensional Stress
Differential Stress. Causes rock to fold or fracture and SQUEEZES rock together.
- most common type found in convergent boundaries.
- cause rocks to fold upward or downward.
Compressional Stress
Differential Stress. Forces SLIDES pass each other in opposite direction.
- most common type found in transform boundaries.
- cause masses of rock to slip
Shear Stress
Rock deformation caused by differential pressure.
Strain
Rocks deform through strain which causes rocks to _____________.
fold and/or crack
Two main types of strain caused by differential stress.
Brittle Formation, Ductile Formation
(+ Elastic Formation)
Types of Strain. Deform, fracture, and fault.
- Rocks may develop cracks, fractures, fissures
- Result to joint or fault
Brittle Formation
Difference of joint and fault:
Joint- fracture without movement
Fault - fracture with movement, there is noticeable displacement)
Types of Strain. Rocks flows in response to stress.
-BENDS, but not break
- change in rock shape/orientation without breaking.
Ductile Formation
Types of Strain. Bends, not breaks, and GOES BACK TO ORIGINAL FORM.
Elastic Formation
Behavior of rocks under different pulling of stress.
- Visible change in shape, loc, size, tilt, or break (due to squeezin nd shearin)
- when rocks or plates are pulled or pushed together, stress may occur.
Two results of deformation:
Folds and Faults
Results of Deformation. This is formed when rocks experience COMPRESSIVE stress and deform plastically.
Folds
Additional infos about FOLDS:
- waves in the stratified rocks of Earth’s crust
- freq seen in outcrop
- reflect the same shape nd style
- cleavage indicates the attitute of axial planes
Three types of folds:
Monocline, Anticline, & Syncline
Types of Folds. A bend in rock layers where oldest rocks are at the bottom, youngest at the top.
(Staircase Bend)
Monocline
Types of Folds. Fold that arches UPWARD where oldest rocks are found at center of it, youngest are covered over them at top.
Anticline
Types of Folds. Fold that bends DOWNWARD which rocks are curved to a center.
Syncline
Additional type of folds;
Chevron: Zigzag
Parasitic: Yung anticline nagkaroon ng syncline (M shape)
Symmetrical - Equal height of anticline & syncline
Asymmetrical - NOT equal in height.
Descriptive features of folds:
Size, Shape, Tightness, Symmetry, Facing & Vergence, Deformation Style Classes, Classification, Orientation of Axial Plane, Thickness of Folded Beds
Results of Deformation. This is a FRACTURE or zone of fractures between two blocks of rock. They produce displacement over time.
Faults
Faults allows the blocks to move _________ to each other.
relative
The a. ____________ is the rock above the fault line while the rock below it is called b._________.
a. Hanging Wall
b. Foot Wall
What are the two types of fault?
Dip-Slip Fault and Strike-Slip Fault
Types of Fault. This is inclined fractures where the blocks has shifted VERTICALLY.
- Movement depend on the inclination of fracture/fault
Dip-Slip Faults
Three classifications of dip-slip faults:
Normal, Reverse, Thrust Fault
Class. of Dip-Slip Fault. The hanging wall above the fault has moved downward relative to the foot wall.
Normal Fault
Class. of Dip-Slip Fault.
- most common faults at DIVERGENT boundaries
- caused by TENSIONAL Stress.
Normal Fault
Class. of Dip-Slip Fault. Hanging wall moves upward relative to the foot wall.
Reverse Fault
Class. of Dip-Slip Fault.
- most common at CONVERGENT boundaries.
- caused by COMPRESSIONAL stress.
Reverse Fault
Class. of Dip-Slip Fault. A break on the Earth’s crust, across which OLDER are pushed above the YOUNGER rocks. Has low inclination.
- It is under reverse fault.
Thrust Fault
What is another term for Strike-Slip Faults?
Transcurrent
Faults on which the two blocks slide past one another. And is caused by Shearing Stress.
Strike-Slip Faults
Two types of Strike-Slip faults?
Right Lateral and Left Lateral
These are common on transform plate boundaries.
Ex. San Andreas Faults
- Movement along the strike.
Strike-Slip Faults
Differences of the types of strike-slip faults:
Right Lateral: Dextral
Left Lateral: Sinistral (Ex. Digdig Fault)
Oblique Fault: Vertical Displacement
