The eight primary P to Sv and Sv to P converted rays generated at a single boundary generally appear at the Earth’s surface as pairs of interfering arrivals consisting of one Sv and one P, of similar kinematic properties. Kinematic equivalence is obtained for the case of a surface source in a laterally homogeneous layered model. The interference, which is a function of focal depth, lateral heterogeneity and the relative amounts of P and Sv energy generated by the source, significantly camplicates the interpretation of the dynamic properties of converted rays. Vertical heterogenity affects converted rays in a multiple fashion as P and Sv segments are both involved. For example, a single low velocity zone will, in general, produce four shadow zones in the primary converted ray branches.