Alessandro Grippo's Earth Sciences Pages

Alessandro Grippo, Ph.D.

A key to lab 14 (Earth History), Geologic Maps and Geologic Structures

 
answers to Lab 14 questions Last Updated  •  November 30, 2016    
Introduction
Strike and Dip

question 1, page 192
N 20° W (340°)

question 2, page 192
N 45° W (315°)

question 3, page 194

  • It is necessary to measure the dip angle perpendicularly to the strike of the inclined bed because that is the only direction in which you can measure the angle of maximum dip
  • Yes, it makes sense from a logical point of view, and it can be proven mathematically.

Folds

question 1, page 197
The width of the outcrop band at the surface is function of the angle of dip. It goes from infinite for a horizontal layer (dip = 0°) to its minimum (the actual thickness of the layer) for a vertical one (dip = 90°)

question 2, page 197
In an anticline, the dips point away from each other; in a syncline, they point towards each other

question 3, page 198
The "V"s are pointing in the same direction of the dips of the fold limb

question 4, page 198

  1. Syncline: the beds in the center are younger
  2. Anticline: the beds in the center are older

question 5, page 198

  1. Look at the "V"s
  2. Look at the dips
  3. Look at the age of rocks
Faults

question 1, page 200

  1. yes
  2. no

question 2, page 200

no

question 3, page 200

yes

question 4, page 200

  1. To the left
  2. Left-lateral strike-slip fault
  3. It would not matter. You could be standing on any side of the fault and look across the fault itself. On whichever block you are standing, the other would always appear to be moving in the same relative direction.

Geologic Maps and Geologic Structure Sections
Geologic Map of the Athens Quadrangle, Tennessee
Mapping Horizontal Beds
Mapping Folded Beds
Structure Contour Maps

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