Geologic Structures, Maps and Block Diagrams

Assignment: Activity 5, pg. 225-226, a-e only, Activity 6, pg. 227-228.

 

Structural geology- the study how geologic units are arranged when deformed.

Attitude- the ___________ of strata which is comprised of three parts

  1. Strike- _________ direction of a line formd by the intersetion of a horizontal plane and an inclined stratum, fault, fracture or other surface.
  2. Dip- the ______ between a horizontal plane and the inclined stratum, fault or fracture.
  3. Dip direction- the direction that water would run down the inclined geologic surface (perpendicular to the horizontal plane).

Unconformity- a surface which has been exposed to ________, causing an undetermined amount of rock to be missing.

There are three types:

  • Disconformity- where there are missing rocks due to erosion, but the strata above and below are __________ to each other.
  • Nonconformity- where sediments cover a metamorphic or ________ erosional surface.
  • Angular Unconformity- where sediments have been deposited over a previously __________, erosional surface.

Faults:

  • Normal fault- caused by the _______ of the hanging wall due to tension
  • Reverse fault- compressional forces cause the hanging wall to ______ ____ over the footwall.
  • Hanging wall- _______ surface of the fault
  • Footwall- ________ surface of the fault
  • Strike slip fault- shear causes this fault to ________ laterally

Folded Structures

  • Anticline (antiforms)- an upfold or convex fold. Oldest rocks are in the ________
  • Syncline (synform)- a downfold or concave fold. Youngest rocks are in the __________.
  • Fold Axis- the imaginary ________ along which the fold appears to have bent
  • Symmetric fold- a bend in the stratum that has a _______ image
  • Asymmetric fold- a bend that is not _______ opposite on each side
  • Plunging fold- a fold that has an axis that is at an ______ with the horizontal plane
  • Plunging anticline- dip towards the nose (closed end)
  • Plunging syncline- dip towards the open end of the strata.