Term

Definition
Dip of a plane in an imaginary vertical plane that is not perpendicular to the strike.
apparent dip </= to true dip 


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Definition
Orientation of a geometric element in space 


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Definition
plane perpendicular to the Earth's surface 


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Definition
The slope of a surface; formally, the angle of a plane with the horizontal measured in an imaginary vertical plane that is perpendicular to the strike. 


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Definition
Azimuth of the horizontal line that is perpendicular to the strike 


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Definition
term for a surface that occurs repeatedly in a body of rock (cleavage, bedding) 


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Definition
a penetrative linear element, such as the intersection between bedding and cleavage or alignment of elongate grains 


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Definition
angle between a linear element that lies in a given plane and the strike of that plane (also rake) 


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Definition
Angle of linear element with earth's surface in imaginary vertical plane 


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Definition
the geographic location of a geometric location 


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Definition
Plane perpendicular to a given geometric element; for example, the plane perpendicular to the hinge line of a fold 


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Definition
angle between a linear element that lies in a given plane and the strike of that plane (also pitch) 


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Definition
Azimuth of the horizontal line in a dipping plane or the intersection between a given plane and the horizontal surface 


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Definition
the line of intersection between two nonparallel surfaces 


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Definition
Azimuth of any feature in map view (strike) 


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Definition
Primary layering in a sedimentary rock, formed during deposition, manifested by changes in texture, color, and/or composition; may be emphasized in outcrop by the presence of parting 


Term

Definition
squeezing unlithified sediment in response to pressure exerted by the weight of overlying layers 


Term

Definition
Beds that have been rotated past vertical in an Earth surface frame of reference, due to this facing is down 


Term

Definition
The tendency of sedimentary layers to split or fracture along planes parallel to bedding; parting may be due to weak bonds between beds of different composition, or maybe due to preference for bedparallel orientation of clay 


Term

Definition
a sequence composed of layers of sedimentary rock 


Term

Definition
(stratigraphic facing) the direction of the younger strata or the direction to the depositional top of beds 


Term

Definition
 disconformity
 angular unconformity
 nonconformity
 buttress unconformity



Term

Definition
beds of the rock sequence above and below the unconformity are parallel to one another, but there is a measurable age difference between the age sequences.
 Disconformity surfaces represents a period of undeposition and/or erosion
[image] 


Term

Definition
unconformities at which strata were deposited on a basement of older crystalline rocks. The crystalline rocks may be either plutonic or metamorphic
[image] 


Term

Definition
strata below the unconformity have a different attitude than strata above the unconformity. beds below are truncated at the unconformity while the beds above the unconformity roughly parallel the unconformity surface. therefore if the unconformity is tilted, the overlying strata are tilted by the same amount.
 Occurrence means that the subunconformity strata were deformed (tilted/folded) then were truncated by erosion prior to deposition of the rocks above the unconformity (Active Tectonism)
[image] 


Term

Definition
(onlap unconformity) occurs where beds of the younger sequence were deposited in a region of significant predepostional topography.
 formed when sea level rises, burying islands with sediment. However along the margins of the island, the layers appear to be truncated by the unconformity. rocks below may/not be parallel to the unconformity
 different from angular in that the younger layers are truncated by the unconformity at the surface.
[image] 


Term

Definition
an interruption in sedimentation, such that there is a measurable gap in time between the base of the sedimentary unit and what lies beneath it 


Term
Steps in Structural Analysis 

Definition
 Descriptive Geometric Analysis (geometric features in rock described by shape and the use of a 3dementional space to describe the structures orientation)
 Kinematic Analysis (determination of the movement paths rocks took during transformation from the undeformed to the deformed state)
 Mechanical Analysis (study of processes on the atomic scale that allows structures to develop)



Term

Definition
Force per unit area acting on a plane



Term
Steno's Laws of Stratigraphy 

Definition
 Law of Original Horizontality  layers of strata are originally deposited horizontally
 Law of Superposition  strata follow one another in chronological, but not necessarily continuous order
 Stratigraphic continuity  strata occur in laterally continuous and parallel layers in a region



Term
Deformation's 3 components 

Definition
 rotation (pivoting of a body around a fixed axis)
 translation (change in position of a body)
 strain (distortion or change in shape of the body)



Term
Brittle Vs. Ductile Deformation 

Definition
 Brittle  loss of cohesion across a mesoscopic discrete surface. Common in Uppercrust
 Ductile  formed by opposite of Brittle, occurs in deeper part of crust



Term

Definition
 deformation  collective displacement of points in a body, the complete transformation from the initial to the final geometry of a body
 strain  changes of points in a body relative to one another, distortion of the body
Deformation is not a vector entity, but a second order tensor (similar to stress) 


Term

Definition
when there is zero internal vorticity (measure of the degree of noncoaxiality) the strain history is coaxial 


Term

Definition
Strain in which the incremental strain axes remain parallel to the finite strain axes during progressive strain 


Term

Definition
strain in which two portions of a body similar in form and orientation before strain undergo relative change in form and orientation 


Term

Definition
strain in which any two portions of a body similar in form and orientation before strain remain similar in form and orientation after strain 


Term

Definition
Strain state of one step in a progressive strain history 


Term

Definition
Incremental strain of vanishingly small magnitude ( a mathematical descriptor) 


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Definition
Strain that compares the initial and final strain configurations (total strain) 


Term

Definition
Strain in which the incremental strain axes rotate relative to the finite strain axes during progressive strain 


Term

Definition
a change in length divided by the original length, dimension less quantity
 expressed as elongation (e)
e=(llo)/lo
l=final length
lo=original length 


Term

Definition
measure change in angle (angular shear) between two lines that were originally perpendicular
 angular shear=ψ
 shear strain=γ=tanψ



Term

Definition
for use in calculations associated with the Mohr circle for strain
 quadratic elongation=λ=(l/lo)^2=(1+e)^2



Term

Definition
root of quadratic elongation, a convenient strain parameter that directly relates to the dimensions of the strain ellipsoid



Term

Definition
a state were one of the strain axes (commonly y) is of the same length before and after strain, although triaxial describe as two demential since y=0 


Term

Definition
plots the ratio of the maximum stretch over the intermediate stretch on the vertical axis and the ratio of the intermediate stretch over the minimum stretch of the horizontal axis
 k=(a1)(b1)=slope of line as it passes through origin
 a=x/y=(1+e1)/(1+e2)
 b=y/z=(1+e2)/(1+e3)
[image] 


Term

Definition
Ramsay diagram uses the natural logarithm of the values a and b and is a modification of the flinn diagram
 ramsay has more advantages in that, small strains that plot near the origin and large strains that plot away from the origin are more evenly distributed. Also allows a graphical evaluation of the incremental strain history because it plots a path along straight lines


