Freeman T. Procedures in Field Geology

Malden: Blackwell Science, 1999. — 95 p. — ISBN: 0-86542-008-4.My purpose in writing this manual is to provide a pocket-size presentation of field procedures without the bulk and cost of a comprehensive textbook. The first part, Tools of the Trade, covers the Brunton compass and Jacob's staff, the Silva compass, and the plane table and alidade-along with principles of map direction and strike and dip. Also, I have included a section on uses of the stereographic net for those who lack hardware and software necessary for the manipulation of field measurements. A second part, Things to Do, presents a variety of procedures commonly undertaken in geologic field courses. The third part, Reference Stuff, provides basic information on topographic maps, trigonometric solutions, and conventional map patterns and symbols. Field procedures described herein are those that have emerged through years of teaching at our University of Missouri's Camp E.B. Branson in the Wind River Mountains of Wyoming. I welcome suggestions for the inclusion of additional procedures in future editions.
Tom FreemanTools of the trade
The Brunton compass
But first-two methods of stating direction
Bearing (or quadrant) method
Azimuth method
Brunton anatomy
Magnetic declination
Magnetic declination defined
Adjusting a Brunton for magnetic declination
Beware of metal objects!
Measuring direction to an object
Using a Brunton as a protractor
Measuring vertical angles
Review-trigonometry of a right-triangle
Solving for map distance represented by slope angle and slope distance
Solving for difference in elevation represented by slope angle and slope distance
Solving for difference in elevation using successive eye-height measurements
Strike and dip-definitions
Recording strike with the right-hand rule
The other right-hand rule
The azimuth method of describing the orientation of and inclined plane
Measuring strike-contact method
Measuring dip magnitude-contact method
Using two outcrops to measure strike and dip
Measuring trend and plunge of a lineation
Measuring the trace of an outcrop
Measuring an inclined stratigraphic section with a Jacob's staff and Brunton
The Silva compass
Weaknesses and strengths
Silva anatomy
Setting magnetic declination on a Silva
Measuring direction with a Silva
Measuring strike and dip-contact method
Plotting directions on a map with a Silva
Using a Silva to measure rake (or pitch)
The plane table and alidade
Beaman scales, type 1 and type 2
Alidade anatomy
Setting up the table and working on a base map
Orienting the table, focusing, adjustments
Reading the vertical arc and vernier
Stadia distance
Procedure-'running the gun'
Computing elevations-forsights
Computing elevations-backsights
A sample format for recording data
The stereographic net
Purpose
Preparing a stereographic net
Planar and linear features
Representing an inclined (dipping) plane
Representing an inclined (plunging) line
Representing the plunge of a line from its rake in an inclined plane
Representing a line formed by the intersection of two planes
Solving for original orientation of structurally tilted cross-beds
Solving for strike and true dip with two apparent dips
Things to Do
Confronting an outcrop-points to ponder
The value of reconnaissance
The utility of field sketches
The importance of contact relationships
Mapping-pace-and-Brunton method
Definition and procedure
Correcting error of closure
Triangulating-intersection method
Resection method
Describing stratigraphic sections-format
Lithic descriptions
Geomorphic profile
Constructing a geologic road traverse
Using contour maps-the 'rules of contours'
Constructing a contour map
Constructing a topographic profile
Constructing a geologic cross-section
Solving for exaggerated dip when the vertical scale is exaggerated
Solving for true dip when a cross-section is not perpendicular to strike
Reference Stuff
Land survey system-latitude and longitude
Townships and ranges
Sections and parcels
Map dimensions and scales
Grid north
Trigonometric solutions of stratigraphic thickness
Where slope and dip are in opposite directions
Where slope and dip are in the same direction
Lithic patterns and symbols
Structural map symbols