<P> Any planar feature can be described by strike and dip . This includes sedimentary bedding, faults and fractures, cuestas, igneous dikes and sills, metamorphic foliation and any other planar feature in the Earth . Linear features are measured with very similar methods, where "plunge" is the dip angle and "trend" is analogous to the dip direction value . </P> <P> Apparent dip is the name of any dip measured in a vertical plane that is not perpendicular to the strike line . True dip can be calculated from apparent dip using trigonometry if you know the strike . Geologic cross sections use apparent dip when they are drawn at some angle not perpendicular to strike . </P>

The direction of a horizontal line on an inclined rock strata