A new technique is presented for the study of seismic reflection profiles. Previous investigations of the reflection of sound from marine sediments have been restricted to the determination of a specular reflection coefficient. This study is based upon the hypothesis that the entire reflected waveform, rather than just the amplitude, contains valuable information on the classification and characteristics of these sediments. The multivariate statistics technique of principal component analysis is proposed for analyzing the variability in the shape and amplitude of the reflected waveform. The results of this analysis are used in conjunction with an improved cluster analysis program to produce maps of sediment distributions for a section of Narragansett Bay, Rhode Island. The groupings produced are in basic agreement with previous studies of the area. Preliminary regression equations are presented for converting the principal components to percentages of sand, silt, and clay.