PLOTTING LINES AND PLANES ON A STEREONET CONTD.

1
PLOTTING LINES AND PLANES ON A STEREONET CONTD.
Pages 698-704
2
Plotting a plane by its dip and dip direction on
a stereonet (also known as DIP VECTOR)

• Dip inclination of the line of greatest slope
  on an inclined plane
• Refers to TRUE DIP as opposed to APPARENT DIP of
  a plane
• 0 apparent dip lttrue dip
• Dip direction is ALWAYS perpendicular to strike
  direction
• The dip and dip direction of an inclined plane
  completely defines its attitude
• Plotted the same way as lines

3
Defining a plane by its POLE (page 698)

• POLE of a plane line perpendicular to the plane
• A plane can have ONLY ONE pole
• The orientation of the pole of a plane completely
  defines the orientation of the plane
• This is the MOST common way planes are
  represented on a stereogram

4
Plotting the pole of a plane (page 698)

• If you have strike/dip/dip direction data, Start
  the same way you normally would for plotting the
  great circle for the plane
• Identify the dip line (the line of greatest
  slope) on the great circle
• The POLE is the line perpendicular to the dip
  line
• To get to the pole of the plane, count 90 from
  the dip line along the E-W vertical plane, and
  mark the point
• You dont need to draw the great circle

5
Measuring the angle between two lines

• Angle between two lines is measured on the plane
  containing both lines
• Plot the points representing the lines
• Rotate your tracing paper so both points lie on
  the same great circle. This great circle
  represents the plane containing both lines
• Count the small circles between those two points
  along the great circle to determine the angle
  between the lines.

6
Measuring the angle between two planes

• Angle between two planes is the same as the angle
  between their poles (this is yet another reason
  for plotting poles instead of great circles for
  planes)
• Plot the poles for the planes
• Rotate your tracing paper so both poles lie on
  the same great circle.
• Count the small circles between those two poles
  along the great circle to determine the angle
  between the two planes.

7
Measuring angle between two planes on stereonet
(lab 3, 9/21-23)
Measure the angles between the pairs of planes
with the given attitudes
Dip/dip direction 38NE 43SE 57SW 23N 65SW 71NW

• Strike
• 342
• S27W
• N35W
• 278
• 132
• N25E

Pair 1
Pair 2
Pair 3
8
Plotting a plane using trend and plunge (or
apparent dip/dip direction) data of two lines
lying on that plane

• Plot the points representing the lines
• Rotate your tracing paper so those two points lie
  on the same great circle
• Trace and label that great circle

9
Plotting a plane from trend/plunge data of two
lines (lab 3, 9/21-23)
Identify the plane containing the following pairs
of lines with the given attitudes
Plunge 67 26 58 59 90 58

• Trend
• 357.5
• 112.5
• 17.5
• 282.5
• 77.5
• 330.5

Pair 1
Pair 2
Pair 3