During core drilling, runs of core up to about three metres long are extracted from the core barrel. The extraction process rotates the core randomly, so that once the core is laid out in core boxes its original orientation is lost, although the orientation of the core axis is generally known. Various down-hole surveying techniques are available for this, and the common usage of 3-D modelling software has lead to holes being generally very well surveyed. <...>

Each of the following pages contains a protractor for a specific size of drill core. 

Choose the appropriate chart for the drill core size. Check the core diameter to choose the appropriate template within each core size grouping.

The protractors are in two groups: beta angle protractors and alpha/beta angle protractors. In practice I find that the beta angle protractor alone is best as it is least cluttered with lines (and alpha angles are easily measured using a protractor). <...>

• Drill core measurement procedures

• Geometrical relationships

• Using GeoCalculator to solve the geometry

• Manual stereographic plotting procedures

• Introduction to HCA wrap-around beta angle protractor templates