In geology, mining, and geotechnical engineering, core angles refer to geometric measurements taken directly from a cylindrical rock sample (a drill core) to determine the real-world orientation of geological features. When a borehole intersects planar structures—such as bedding, joints, faults, or fractures—the features appear as ellipses on the surface of the cylindrical core.
Engineers and geologists use specific instruments like a Kenometer to record these angles. The two primary angles measured are Alpha (α) and Beta (β). The Primary Core Angles
Alpha (α) Angle: This is the maximum angle between the geological plane (the planar fabric) and the long central axis of the drill core. It dictates how steeply the structure cuts across the core sample itself.
Beta (β) Angle: This is a rotational angle measured clockwise (from 0° to 360°) around the circumference of the core. It is measured from a designated “core orientation line” (usually the bottom or top of the core) to the highest or lowest point of the feature’s ellipse.
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