Brunton GeoTransit, Operator'S Manual

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Strike & dip measurements are planar measurements
taken when direct contact is made with the outcropping.
5.1 Strike Measurement
Strike is the direction of a line that is formed by an inter-
section of an imaginary horizontal plane and an inclined
surface that is being measured.
1. Open both the cover and large sight until both extend in
a straight line.
2. Place transit along a horizontal line on the inclined rock
surface. (Fig 26)
•
Hint: Place on a writing tablet to extend the horizontal line.
3. Hold level by centering bubble in the round level.
4. Read strike angle at either the “
N ” or “ S ” tip.
Some people recommend the strike measurement be the largest angle out of “ N ” and “ S ”, so
that there is no confusion between the strike and dip angle.
5.2 Dip Measurement
Dip is the vertical angle (inclination) of the rock surface, measured from horizontal.
1. Open the cover and large sight until they both extend in a straight line.
4.2.a Height Measurement Using Vertical Angles
1. Sight inclination, as described in section 4.2.
2. Apply height calculation as shown in figure 24A or 24B.
Note: Do not calculate tangent of an angle by adding tangents of two smaller angles.
Example: Tan(60°)
≠
Tan(30°) + Tan(30°) Find Tan(60°) from a table, use a calculator, or
step back until angle of inclination is less than 45°, then use tangent table on the GEO lid.
4.2.b Height Measurements Using % Grade
1. Sight % grade using level or sloping ground, same as in Figures 24A & 24B .
2. Apply height calculation, as show in figures 25A & 25B.
14 13
Below Object Base
Height = (TanA - TanB) x Distance
Example: A = 38
°
, B = 10
°
& Distance = 75 ft.
Height = (Tan38
°
- Tan10
°
) x 75’
Height = (.781 - .176) x 75’
Height = (.605) x 75’
Height = 45.38 ft. = 45’
Above Object Base
Height = (TanA + TanB) x Distance
Example: A = 36
°
, B = 10
°
& Distance = 50 ft.
Height = (Tan36
°
+ Tan10
°
) x 50’
Height = (.727 + .176) x 50’
Height = (.903) x 50’
Height = 45.15 ft. = 45’
Above Object Base
Height = (A + B) x Distance
Example: A = 72.7%, B = 17.6% & Distance = 50 ft.
Height = (72.7% + 17.6%) x 50’
Height = (.903) x 50’
Height = 45.15 ft. = 45’
Below Object Base
Height = (A - B) x Distance
Example: A = 78.1%, B = 17.6% & Distance = 75 ft.
Height = (78.1% - 17.6%) x 75’
Height = (.605) x 75’
Height = 45.38 ft. = 45’
Figure 25A Figure 25B
Figure 24A Figure 24B
Height Measurement
Above Object Base
Height Measurement
Below Object Base
Figure 26
5 -- Strike & Dip Measurement