Introduction to the Brunton Compass Parts of the

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: 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: 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. Mc. Bride) Cross-Section: Dipping Strata

strike Aerial View: Strike of Dipping Strata (E. Mc. Bride)

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