Dip angle
Dip is the inclination of a given feature, and is measured from the steepest angle of descent of a tilted bed or feature relative to a horizontal plane. True dip is always perpendicular to the strike. It is written as a number (between 0° and 90°) indicating the angle in degrees below horizontal. It can be accompanied with the rough direction of dip (N, SE, etc) to avoid ambiguity. The direction can sometimes be omitted, as long as the convention used (such as right-hand rule) is known. A feature that is completely flat will have the same dip value over the entire surface. The dip of a curved feature, such as an anticline or syncline, will change at different points along the feature and be flat on any fold axis.
Angle