Tectonic Structures Tectonics is the study of crustal deformation and structural behavior
Plate Tectonics is the deformation and structural behavior of crustal plates
Stress Stress is any force which acts to deform rocks
Compression - a stress that acts to press or squeeze rocks together
Tension - a stress that acts to stretch a rock, or pull a rock apart
Shear - a stress which acts tangential to a plane through a body, causing two contiguous parts to slide past each other
Structural Behavior As a general rule
Rocks tend to have a relatively high compressive strength
Rocks tend to have a relatively low tensile and shear strength
Strain When a stress is applied, deformation may occur
Depending on the rate of stress
Depending on the amount of stress
Strain is the change in shape or volume of a body as a result of stress; deformation
Ductile Deformation Brittle and Ductile deformation
During ductile deformation rocks bend or flow
Folding or bending of material without breaking
Specifically defined as a rock that is able to sustain, under a given set of conditions, 5-10% deformation before fracturing
Folds can be microscopic in size or kilometers in extent
Anticlines Folds which arch up
. 
Synclines Folds which sink down
Monoclines Folds in which rock layers on both sides of the fold are horizontal but at different levels
Domes Folds which are equivalant to anticlines, but are comprised of layers which are shaped like an inverted bowl
Basins Folds which are equivalant to synclines, but are comprised of layers which are shaped like a bowl
Brittle Deformation During brittle deformation rocks break or fracture
Two main styles of fracture, joints and fualt
Both are the result of relatively rapid stress
For example: modeling clay will break if stress is applied rapidly, but will bend if stress is applied slowly
Joints Joints are fracture surfaces along which there has been no displacement
Joints can form from compressional, tensional and shear stress, and can range in size from microscopic to kilometers in length
Joint sets and jointing has a major influence on landform development
Erosion is able to occur at a faster rate along joints
Faults Faults are fractures along which there has been displacement of the material on either side of the fault
Faults are classified based on
the sense of movement (the direction in which the blocks on either side of the fault move) - this is controlled by the type of stress that is applied
the orientation of the fault surface (the angle of the plane of fracture)
Fault Terminology Fault Plane - the plane along which the rock or crustal material has fractured
Hanging Wall Block - the rock material which lies above the fault plane
Footwall Block - the rock material which lies below the fault plane
Strike-Slip Faults Fault plane is generally vertical
Movement is horizontal due to shear stress
Left-Lateral Strike-Slip - displacement is such that the material on the other side of the fault appears to be displaced to the left
Right-Lateral Strike-Slip - displacement is such that the material on the other side of the fault appears to be displaced to the right
Normal Faults Fault plane is oriented between 30 and 90 degrees (measured from horizontal)
Movement has both a horizontal and vertical component
Normal faults result from tensional stress and results in the hanging wall moving down relative to the footwall
Detachment Faults Fault plane is at less than 30 degrees
Movement is more horizontal than vertical due to the low angle of the fault plane
Develop due to tensional stress
Reverse Faults Fault plane is oriented between 30 and 90 degrees (measured from horizontal)
Movement has both a horizontal and vertical component
Reverse faults result from compressional stress and results in the hanging wall moving up relative to the footwall
Thrust Faults Fault plane is at less than 30 degrees
Movement is more horizontal than vertical due to the low angle of the fault plane
Develop due to compressional stress
Horsts and Grabens Horsts are up thrown blocks bounded on either side by parallel normal faults.
Grabens are downthrown blocks bounded on either side by parallel normal faults
Half-Graben Half-grabens develop when parallel faults on either side of a block develop, but the block becomes tilted instead of dropping down as in a graben
Fault Map Symbols 
Measurement of Orientation Strike - compass direction of the outcrop
- the line formed by the intersection of a horizontal plane with the structure
Dip - the angle between the horizontal plane and the planar surface being measured
Dip is always perpendicular to Strike
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