Transcript Slide 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)
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)
Uses of the Brunton Compass
• Locate North
• Sight Angles
- measuring height / thickness of a feature
• Bearing
• Strike and Dip
• Trend and Plunge
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.
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).
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.
W
E
Horizontal
Dip Angle
(E. McBride)
Cross-Section: Dipping Strata
W
E
Horizontal
Dip Angle
(E. McBride)
Cross-Section: Dipping Strata
Aerial View: Strike of Dipping Strata
(E. McBride)
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
Trend and Plunge
Linear Glacial Striations (Maine)
Map Symbols
(map view)
strike and dip
45º
strike and dip (vertical)
strike and dip (horizontal)
Bring to Lab
• Course Packet
• Brunton Compass
• Field Notebook
• Ruler (metric)
• Protractor
• Calculator (tangent)
• Clipboard