How to Use Compass Clinometer
Clinometer compass is a versatile tool used primarily in geology, surveying, and outdoor activities to measure angles of slope, elevation, and direction. It combines the functionalities of a clinometer (for measuring angles) and a compass (for determining direction).
Compass Clinometer combines two instruments: a compass for direction and a clinometer for measuring angles. Geologists and hikers often use them to measure the tilt of rock layers (dip) and their direction (strike).
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| Compass Clinometer parts |
Compass Clinometer Parts
Compass Needle:
A magnetized needle that aligns itself with the Earth's magnetic field, pointing toward magnetic north. This helps users establish a reference direction.
Indicates magnetic north and helps determine the direction of a slope or geological feature.
Level Vial:
A small glass tube filled with liquid and an air bubble that indicates whether the compass is held level. Accurate measurements of angles require the instrument to be perfectly horizontal.
Ensures that the instrument is held horizontally, providing accurate angle measurements.
Protractor Scale:
A circular or semicircular scale marked in degrees, which allows users to read the angle of elevation or depression directly. This scale is typically calibrated from 0° to 90°.
Typically marked in degrees, it allows users to measure the angle of slope or elevation directly.
Sight Vane or Peep Sight:
A small aperture or sighting mechanism on the compass that allows the user to aim at a distant target accurately. This feature is crucial for taking precise angle measurements.
Used for aiming at distant points to take precise measurements of angles.
Base Plate:
A flat platform on which the clinometer compass rests. It often has a ruler or measuring scale along its edge for additional measurements.
Provides a stable platform for the clinometer compass, often featuring a ruler for additional measurements.
Adjustable Arm (if applicable):
Some clinometer compasses have an adjustable arm that allows for more versatile measurement angles, especially in steep terrain.
Sighting mirror (optional): Some clinometer compasses have a mirror that allows you to sight an object indirectly while keeping the compass level.
Here's a guide on how to find the dip and strike of a rock layer using a compass and clinometer, with images to illustrate the steps:
The exact order that you complete the steps and obtain the strike and dip of the plane is not crucial; this will depend on the instrument used, field conditions and personal preference. What is important is ensuring that you record the three pieces of information (strike, dip magnitude and dip direction).
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| Compass Clinometer |
Note that the order of the steps in Figures is different to take account of the easiest way to measure a dipping plane with the different instruments. If this technique is new to you, or the reading seems unreasonable, or the bedding surface is not ideal, take a second or even third reading and use the average or the best one.
Determining the Orientation of a Dipping Plane
1-General orientation
Find a good surface that is representative of the overall dip of the plane to measure. Determine the general direction of dip by looking at the plane or you can pour fluid over the bedding plane to see which way it runs.In some cases it may be necessary to smooth out the variations on the surface by placing a notebook or clipboard on the bedding plane, but take care to ensure that this is not biased by a small irregularity. Hammer near left hand side shows the plane chosen in this case.
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| 2. Set the clinometer mode |
2. Set the clinometer mode
3. Dip magnitude
Place the long edge that is at the base of the clinometer scale on the bedding plane, with the long edge of the compass-clinometer parallel to where you estimate the maximum dip direction lies (i.e. pointing down the slope).
While looking at the clinometer reading, carefully rotate the compass-clinometer device slightly (as shown by the arrows) to find the line of maximum dip.
Read off the maximum dip. In this case it is 12°. Note that the dip can be read from either side of the Silva-type compass-clinometer.
4. Strike direction
The strike direction is exactly perpendicular to the dip direction, so remembering where the maximum dip lies, lift the compassclinometer and place the long edge of the compass-clinometer along the line of strike.
Pivot the compass-clinometer window (as shown by the red arrow) until it is horizontal.
Rotate the compass dial so that the compass needle lines up with the red outline for the north direction, checking that the compassclinometer is still horizontal. Take the reading of the strike from the dial. In this case it is 008° or the other end of the line, 188°.
You can double check that the strike direction is correct by placing the compass on its long edge along the strike line and checking that the dip is 0° (don’t forget to adjust the compass to the clinometer mode (step 2)).
5. Dip direction
The last measurement is the direction of dip to the nearest cardinal point (e.g. NW or SE, E or W). In this case it is E.
6. Record
Record the orientation of the plane in your notebook; in this case 008/12E. Note that the strike is always recorded as a 3-digit number to avoid any confusion and that the degree symbols are not normally shown to prevent any confusion with zeros.
Tips:
- For accurate readings, ensure the compass clinometer itself is level.
- Calibrate your compass clinometer regularly according to the manufacturer's instructions.
- When using the mirror, be careful not to look directly at the sun.
Using the Mirror (optional):
If the slope is hard to reach directly, use the sighting mirror.
Hold the compass clinometer level and look through the peep sight.
Tilt the mirror until you see the object you want to measure (like the top of a tree) through the peep sight and the mirror.
The clinometer scale will be reflected in the mirror. Read the angle where the level indicator intersects the reflected scale.
By following these steps and practicing regularly, you can effectively use a clinometer compass for navigation, surveying, outdoor activities, and other applications requiring precise measurement of direction and angles.
Summary
A clinometer compass is an essential tool in various fields, providing critical data for understanding slopes, elevations, and geological formations. By mastering its use, professionals and outdoor enthusiasts can gain valuable insights into the landscapes they study or traverse.