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Explore the essential components, functions, and practical applications of the Brunton Compass for measuring orientation data like bearing, strike and dip, trend and plunge. Understand how to use it to determine angles, orientation, and location on maps efficiently.
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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 strike (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)
strike and dip strike and dip (vertical) strike and dip (horizontal) Map Symbols (map view) 45º
Bring to Lab • Course Packet • Brunton Compass • Field Notebook • Ruler (metric) • Protractor • Calculator (tangent) • Clipboard