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Compressional(P)-wave attenuation, shear(S)-wave attenuation, and shear(S)-wave velocity measurements, compiled for fine-grained, unconsolidated sediments, show trends that do not support empirical relationships [Hamilton, J. Acoust. Soc. Am. 68, 1313–1340 (1980); in Acoustics and Ocean Bottom (F. A. S. E. Specialize Conf., Madrid, 1987)] commonly used for geoacoustic modeling. The exception is compressional-wave attenuation data, from 10 Hz to 500 kHz, that essentially follow a frequency dependence of f1 (±2 standard deviations). P-wave attenuation with depth is difficult, if not impossible, to predict given the variability in the data. Examination of several attenuation/depth profiles indicates that those of Mitchell and Focke [J. Acoust. Soc. Am. 67, 1582–1589 (1980)] may be the best choice for predicting P-wave attenuation with depth at the present time. The assumption that S-wave and P-wave attenuations are proportional [Hamilton, J. Acoust. Soc. Am. 60, 334–338 (1976c); in Acoustics and Ocean Bottom (F. A. S. E. Specialize Conf., Madrid, 1987)] is not supported by the data. S-wave attenuations calculated from effective stress mimmick the data, however, suggesting this as a better method for predicting S-wave attenuation with depth. S-wave velocity/depth profiles fall into high- and low-velocity groups that (1) reflect gross differences in sediment texture, and (2) demonstrate the importance of sediment characterization in order to select an appropriate velocity/depth function.

Detailed X-ray diffraction analysis of cores taken in the eastern equatorial Atlantic suggest that during approximately the last 600,000 yr a relatively constant background of clay mineral deposition has existed on which are superimposed large oscillations in quartz input (relative to illite). The quartz is transported from the Sahara Desert by the northeast trade winds and the quartz/illite oscillations appear to reflect past changes in the transporting effectiveness (intensity) of the trade winds. Comparison of the quartz/illite variations with paleotemperature variations for the northeast Atlantic suggests that major inputs of quartz correlate with cold periods and that warm periods correlate with low quartz input. The parallelism between the curves indicates a fundamental link between trade wind intensity and past climatic fluctuations, and further suggests that the changes of intensity are closely atuned to temperature fluctuations in the northern latitudes. The relationship between the quartz/illite variations and wind intensity is complicated by the fact that other climatically controlled factors may also affect quartz deposition in the equatorial Atlantic.

Exaimnination of ultrathin sections of "undisturbed" marin1e sediments from the Gulf of Mexico indicates that they are chlaracterized by a loose, open, random arrangement of particles. The microstructures do not appear to conform entirely to either cardhouse or honeycomb structures.

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