[en] The mechanical properties of rocks and soils can be calculated from the shear-wave velocity, V_s, the compressional-wave velocity, V_p, and the density, or from (V_S/V_P) ratios and the density. Therefore, determination of (V_S/V_P) ratios is an important tool to assist with lithological identification and many associated applications. In most geologic settings, mixtures of different materials are quite common, and it is important to understand the effect of thin laminations on measured (V_S/V_P) ratios. An equation is derived for (V_S/V_P) in transversely-isotropic materials. It is found that even small amounts of a second component, such as 10% shale, can change (V_S/V_P) ratios significantly from that of a pure end member, such as sandstone. Case studies will illustrate some practical applications. 32 refs., 6 figs