Introduction to the Brunton Compass

1
Introduction to the Brunton Compass

• Parts of the Compass
• Uses of the Brunton Compass
• - Bearing
• - Strike and Dip
• - Trend and Plunge
• Map Symbols

Text Compton, p. 16-21 34-39 Measurement of
Attitude and Location Lab 1 (website)
2
Parts of the Compass

• Compass Face
• - Arrow (white tip North)
• - Directional Degrees (Quadrant or Azimuth)
• Clinometer Scales in Degrees and Grade
• Levels
• - Bullseye Level
• - Cylindrical Level
• Mirror
• Sighting Arm
• Dampener
• Magnetic Declination (6.5 E of N)

3
Uses of the Brunton Compass

• Locate North
• Sight Angles
• - measuring height / thickness of a feature
• Bearing
• Strike and Dip
• Trend and Plunge

4
Bearing
Bearing direction from one point to another
point.

• 1-directional line
• Quadrant Notation N or S____ E or W
• Azimuth Notation _____

Note With sighting arm pointing to object,
always read the white tip of the needle.
5
Strike and Dip
Strike Direction of the line of intersection
between a tilted plane and a horizontal plane.

• 2-directional line
• Azimuth Notation _____

Note Read the end of compass needle that makes
dip direction to the right of the strike
direction (Right-Hand-Rule).
6
Strike and Dip
Dip Angle between a tilted plane and a
horizontal plane that is perpendicular to strike.

• Maximum angle ( 90º )
• Notation ____ N, S, E, W, NE, NW, SE,
  SW

Note If use Right-Hand-Rule, dip direction is
implied.
7
(E. McBride)
Cross-Section Dipping Strata
8
(E. McBride)
Cross-Section Dipping Strata
9
Aerial View Strike of Dipping Strata
strike
(E. McBride)
10
Trend and Plunge
Trend bearing of a linear feature.

• 1-directional Line
• Measured in Direction of Plunge
• Azimuth Notation _____

Plunge angle between a tilted linear feature
and a horizontal plane.

• Notation ____

Note written as plunge, bearing
11
Trend and Plunge
Linear Glacial Striations (Maine)
12
Map Symbols
(map view)
45º
13
Bring to Lab

• Course Packet
• Brunton Compass
• Field Notebook
• Ruler (metric)
• Protractor
• Calculator (tangent)
• Clipboard