STRIKE AND DIP

MEASURING STRIKE

Planar Feature:If the horizontal extension of planar feature i.e. bed is exposed then measure strike by following these steps:

1) Open the Brunton Compass such that needle north must be in direction of clinometer north.

2) Touch the upper edge of Brunton Compass for escarpment face (dipping away from you) or its lower edge for other face (dipping towards you) of bed with the horizontal extension of bed.

3) Move the Brunton Compass up and down keeping its edge touched with the bed, center the round level bubble and press pin lock.

4) Note the azimuth scale reading with respect to north tip of needle that is the strike of bed. E.g. N50E or 050.

If the horizontal extension of planar feature i.e. bed is NOT exposed then place a book parallel to and in direction of bed dip. Then follow above mentioned steps with that book considering it as horizontal extension of the bed to measure its strike.

Linear Feature:There are two methods for measuring strike/trend of linear feature:

(a) With Contact:Place a book vertically parallel to and in direction of linear feature. Then follow above mentioned steps with that book considering it as vertical extension of the linear feature to measure its trend.

(b) Without Contact:1) Attach a pen with linear feature keeping it dipping in the direction of linear

feature.

2) Open the Brunton Compass such that its mirror part is at 120 degrees and its long sight is at 60 degrees.

3) Look from peep sight through Mirror Window down to the pen tip.

4) Also center the round level bubble and lock the needle. Note azimuth which is its trend.

MEASURING DIP

Planar Feature:We can find Dip Magnitude and Direction of planar feature by drawing a strike line on it and then following these steps:

A- Dip Magnitude:1) Open the Brunton Compass such that place its longer side perpendicular to strike

line on bed surface/plane.

2) Rotate Clinometer Arm until long level bubble is centered.

3) Note the clinometer scale reading. E.g. 12 degrees.

B- Dip Direction:1) Place Brunton Compass on bed surface/plane with back of mirror part flat on the

plane.

2) While keeping mirror part flat, move Compass Window up and down to make round level bubble centered.

3) Compass Needle shows Dip Direction with respect to its north tip. E.g. NW.

Linear Feature:There are two methods for measuring dip/plunge magnitude of linear feature:

(a) Without Contact:1) Attach a pen with linear feature keeping it dipping in the direction of linear

feature.

2) Open the Brunton Compass such that fold the Mirror part into the Compass Window at 60 degrees and keep Compass Window at 180 degrees.

3) Also fold peep sight.

4) While holding the Compass from its edge look from peep sight through Mirror Window down to the pen tip.

5) Rotate Clinometer Arm to make long level bubble centered and note the clinometer scale reading. E.g. 12 degrees.

(b) With Contact:Same as in case of planar feature.

TRIANGULATION

There are different methods used for locating your position on globe. One of them is Triangulation method in which we can locate our position on Topographic Map with the help of Brunton Compass. Following are the steps included:

1) Adjust the Compass for magnetic declination by Shadow Stick method.

2) Identify two features on map and also on ground.

3) Open the Brunton Compass such that Mirror part is at 120 degrees, Compass Window is at 180 degrees and long sight is pointed away from you at 90 degrees.

4) Sight the first feature through long sight in the mirror, balance round level bubble and read azimuth scale reading.

5) Place Brunton Compass on Topographic Map with its long edge parallel to N-S grid lines of map.

6) Rotate Brunton Compass and Map together until needle north and clinometer north coincide.

7) Now Map is oriented. Place the long edge of Brunton Compass on that identified feature of map and rotate the Brunton Compass until needle shows reading that you sighted off.

8) Draw a line along edge of Brunton Compass which shows that you are somewhere along this line.

9) Repeat this whole process with the second known feature on ground and map to draw another line.

10) Extend both drawn lines and the point where they intersect is your location.