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Struc Geology / Maps
Chapter 9
Question | Answer |
---|---|
Structural Geology | The study of the architecture or shape of the earth |
Strike | The compass orientation of the line of interseciton between a horizontal plane and a planar feature, such as a rock layer of fault |
Dip | The angle between a tilted layer and a horizontal plane |
Fold | Rocks bent into a series of waves. Result form compressional forces which shorten and thicken the crust |
Anticline | Up-folded, or arched rock layer; shaped like an "A" in cross section |
Syncline | Down-folded rock layer; shaped like the bottom of an "S" in cross seciton |
Symmetrical Fold | limbs are mirror images |
Asymmetrical Fold | limbs are not mirror images |
Overturned Fold | One limb is tilted beyond verticle |
Where folds "die out" they are said to be | Plunging |
Faults | Breaks in rocks along which movement has taken place |
Dip-slip Fault | Movement along the dip (inclination) of a fault plane |
Normal Fault | Hanging wall block moves down; caused by tensional forces; prevalent at spreading centers |
Reverse (Thrust) Fault | Hanging wall block moves up; caused by compressional forces |
Horst | Foot wall |
Graben | Hanging (Head) wall; german for grave |
Strike-slip Fault | Dominant displacemet is horizontal and parallel to the trend (Strike); a transform fault |
Left Lateral Strike-slip fault | Fault across from you is moving to the Left |
Right Lateral Strike-slip fault | Fault across form you is moving to the Right |
Transform Fault | large strike-slip fault that cuts through the Lithosphere; often associated with plate bounderies; Ex: San Andres Fault |
Joints | Fractures with NO definite movement; Formed when rocks in the outer-most crust are deformed |
Geologic Map | a map that shows the locations, kinds, and orientations of rock units, as well as structural features such as faults and folds |
Topographic Map | A map that shows the shape of the ground surface, as well as the location and elevation of surface features, usually by means of contour lines |
Geological Cross Section | A diagram that shows geological features that occur underground |