In
structural geology
Structural geology is the study of the three-dimensional distribution of rock units with respect to their deformational histories. The primary goal of structural geology is to use measurements of present-day rock geometries to uncover informatio ...
, rake (or pitch) is formally defined as "the angle between a line
r a featureand the
strike
Strike may refer to:
People
* Strike (surname)
Physical confrontation or removal
*Strike (attack), attack with an inanimate object or a part of the human body intended to cause harm
*Airstrike, military strike by air forces on either a suspected ...
line of the plane in which it is found", measured on the plane. The three-dimensional orientation of a line can be described with just a plunge and trend. The rake is a useful description of a line because often (in geology) features (lines) follow along a planar surface. In these cases the rake can be used to describe the line's orientation in three dimensions relative to that planar surface. One might also expect to see this used when the particular line is hard to measure directly (possibly due to outcrops impeding measurement). The rake always sweeps down from the horizontal plane.
Fault motion
Rake is used to describe the direction of
fault motion with respect to the strike (measured anticlockwise from the horizontal, up is positive; values between −180° and 180°):
* left-lateral strike slip: rake near 0°
* right-lateral strike slip: rake near 180°
* normal: rake near −90°
* reverse/thrust: rake near +90°
See also
*
Strike and dip
Strike and dip is a measurement convention used to describe the orientation, or attitude, of a planar geologic feature. A feature's strike is the azimuth of an imagined horizontal line across the plane, and its dip is the angle of inclination m ...
References
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{{Structural geology
Structural geology