dip — Oil & Gas Glossary
The angle between a planar feature, such as a sedimentarybed or a fault, and a horizontal plane. True dip is the angle a plane makes with a horizontal plane, the angle being measured in a direction perpendicular to the strike of the plane.Apparent dip is the angle measured in any direction other than perpendicular to the strike of the plane.
Detailed Explanation
Given the apparent dip and the strike, or two apparent dips, the true dip can be computed.