Knowledge of the relation between sonic velocity in sediments and rock lithology is one of the keys to interpreting data from seismic sections or from acoustic logs of sedimentary sequences. Reliable correlations of rock velocity with other petrophysical parameters, such as porosity or density, are essential for calculating impedance models for synthetic seismic sections (BIDDLE et al., 1992; CAMPBELL and STAFLEU, 1992) or identifying the origin of reflectivity on seismic lines (SELLAMI et al., 1990; CHRISTENSEN and SZYMANSKI, 1991). Velocity is thus an important parameter for correlating...