Crustal Deformation 1
This is the change that occurs when stress is applied to a body of rock. It can involve a change in the shape of the rock, the volume occupied by the rock mass, and/or the location of the rock mass.
What is strain?
A. These are tensional features along which there is no significant movement. Most occur in the outermost crust where the rock is brittle. B. A type of jointing in granite due to a release of pressure. Its progression has been described as if one were peeling an onion.
A. What are joints? B. What is sheeting?
A type of brittle strain that can occur during (1) compressional forces or (2) tensional forces.
What are (1) faults and (2) fractures?
A fold in which the beds are arched upward and the fold's limbs dip away from the axial plane; when eroded, the exposed surface rocks get younger further from the axial plane.
What is an anticline?
A circular, or slightly elongated, structurally up-warped area. When eroded, the oldest rocks are exposed in the core of the structure.
What is a dome?
A. The force applied to a given area of rock. B. The three basic types of stress.
A. What is stress? B. What are compression, tension, and shear?
The three types of stress that can act on a body of rock.
What are compression, tension, and shear?
A list of four factors that influence the strength of a rock.
What are temperature, confining pressure, rock type, and time?
This is a measure of an inclined plane's (layer of rock, for example) deviation from the horizontal. It is measured in a direction that is at right angles to its strike.
What is the dip?
A fault in which the hanging wall has been displaced downward relative to the footwall. This type of fault occurs under the influence of tensional stress.
What is a normal fault?
This is a list of the three basic types of strain.
What are elastic strain, brittle strain, and ductile strain?
A type of ductile strain that occurs as a result of compressional stress.
What is folding?
Two related types of brittle strain that occur as a result of tensional stress. Tension pulls blocks of rock away from each other.
What is (1) normal faulting and (2) horst and graben block faulting?
A fold whereby the axial plane is vertical; the limbs on either side of the axial plane have the same amount of dip; the axial plane is a plane of symmetry.
What is a symmetrical fold?
A circular, or slightly elongated, structurally down-warped area. When eroded, the youngest rocks are exposed in the core of the structure.
What is a basin?
A type of fault in which displacement is horizontal and parallel to its strike. It occurs under the influence of shear stress. The San Andreas Fault is a special case of this type of fault, called a transform fault.
What is a strike-slip fault?
The plane that passes through the axis (hinge line) of a fold.
What is the axial plane of a fold?
A fold in which the beds are arched downward and the fold's limbs dip toward the axial plane; when eroded, the exposed surface rocks get older further from the axial plane.
What is a syncline?
A fold in which its hinge line (axis) is inclined to the horizontal.
What is a plunging fold?
A fault in which the hanging wall has been displaced upward relative to the footwall. The fault plane dips at an angle of 45 degrees or more. This type of fault occurs under the influence of compressional stress.
What is a reverse fault?
The line of maximum curvature of a fold.
What is the axis or hinge line of a fold?
The sides of a fold that extend away from the axial plane of the fold.
What is the limb of a fold?
This is the direction of a line formed by the intersection of an inclined plane and a horizontal plane. For example, the line formed by the intersection of a rock layer (strata) with the Earth's surface.
What is strike?
A fold whereby the axial plane is inclined (tilted away from vertical); the limbs on either side of the axial plane do not have the same amount of dip.
What is an asymmetrical fold?
A reverse fault in which the fault plane dips at an angle of less than 45 degrees. Like the reverse fault, this fault also occurs under the influence of compressional stress.
What is a thrust fault?